Most have not delved six feet beneath the surface, nor leaped as many above it. We know not where we are.

Henry David Thoreau

Simple observation, unhurried and deliberative, reveals much about life on the beach but little about life beneath the waves. Floating leaves, submerged vegetation, compromised water clarity, water depth, and reflections off a lake surface often obscure the underwater world. Much as peering into a forest from a helicopter hovering above the treetops, the constrained view from a boat or end of a dock gives scant account of the mostly unseen world below.

My curiosity about this invisible world surfaced when, as a kid, I discovered I could take a deep breath then dive and cruise the bottom with eyes open wide. Scurrying crayfish, clam tracks, water insects, and other unfamiliar sights fascinated me. Between visits to lakes I even practiced holding my breath to lengthen the duration of my dives.

At first I obeyed Mother and the beach rules and stayed within designated swimming areas. Later I discovered such sandy places are wastelands of emptiness compared to what lurked out of bounds. The truly fascinating sights, all many of strange creatures and tiny fish, inhabited edges of weed beds beyond buoys and roped-off zones.

A sabbatical trip to Florida in my early years of teaching reintroduced me to underwater haunts and to prescription goggles. Watching a large crab on the sea floor while snorkeling in the Keys, I wondered, why can’t I do this at home? Water too cool? Lakes too murky? Expectations that only coral reefs are worth seeing?

I have come to this small clear lake in east-central Minnesota to snorkel in a body of freshwater for the first time. I paddle my canoe past the swimming beach, along a wooded shore, and tie up to a birch tree that has fallen across cattails into the lake. With mask, snorkel tube, and fins, I flop onto my belly in the shallow water and wiggle and flipper and belly-scrape my way into the lake.

I submerge and look out among scattered plants. Poof—out of nowhere—as though sprung from a magician’s hat, six tiny sunfish appear. They move toward me, as though curious as to my intentions. More fish appear, blue gills and pumpkinseeds of all sizes, several dozen in all. The gathered throng remains politely motionless, as though expecting me to call the meeting to order, or begin preaching, or deliver long-awaited news from the world above. Several fish, larger than the rest, hold back behind the crowd, eyeing me more warily than others. I turn and—zip—all vanish into the grove of plant stems that surrounds us.

I swish my fins slowly, leave the clump of plants, and head down the shore where a tangled mass of grayish-green stems blankets the bottom as far as I can see. The plants feel springy and crusty, like touching loosened steel wool, or blueberry brush. I pull up a handful, surface, lift my mask, and take a sniff. (Quirky people, biologists. We’ve an almost unconscious habit of checking new discoveries with our noses.) It smells like skunk. Identity revealed. It is the Chara I first met in aquatic plants class. Technically, it’s not a plant at all but a plant-sized green alga. Its crustiness comes from a thin layer of calcareous marl that accumulates over its surface. I dive to look more closely. A school of minnows scatters in front of me, melting into the minute labyrinthine spaces of the finely branched Chara. What fantastic hiding places for young fish and the microscopic life on which they feed. Much of the lake’s bottom just offshore is a vast Chara meadow.

Some lake cabin owners do not appreciate Chara, preferring sand beneath their toes to softly crunching algae. Yet Chara keeps waves from riling bottom mud and dirtying the water. Its tiny spaces provide sanctuary for waterfleas that sally forth to eat algae that would otherwise make the lake murky green.

Ahead of me a group of spindly, stringlike stems spiral lazily to the surface. Each stem ends in a dainty white flower the width of a pencil eraser, so small and inconspicuous, from a boat one might not even realize they are flowers. Wild celery. Vallisneria.

I also notice tiny white floating specks no larger than the diameter of pencil lead. I recognize them as male Vallisneria flowers, floating at the whims of the winds perchance to encounter female flowers of their species.  Few sexual strategies are as delightfully peculiar as those of this plant. Male flowers grow at depth.  When mature, each is sealed with a bubble of air in a special encasement and released. The buoyant bubble floats to the surface, where the capsule bursts open, releasing the male flower to drift about the lake. Female flowers create a dip in the water’s surface film, producing a slope, a miniaturized version of a children’s playground slide, that leads to themselves. When a male flower sails close enough to the sloped water, it glides down the slide into the embrace of its mate. How romantic.

Ducks and swans and other wildlife love Vallisneria and eat every part of the plant. Canvasback ducks are known to change flight routes to seek it out.  The scientific name for the canvasback, Aythya vallisneria, acknowledges its fondness. Wild celery also attracts marsh and shore birds and muskrats and makes good fish habitat.

My fins propel me toward another group of plants and more fish appear. As one group swims off, another replaces it. Several dozen at a time are not uncommon. Not all are sunfish. Often, a large largemouth bass appears, or an occasional small perch hovers at the edge of a sunfish school, then wanders away, obviously less curious about me than the sunfish. Oh, the lake life I have missed from the canoe!

Streams of incredibly tiny bubbles, each the size of the head of a pin, emerge from the tips of several plants. Like so many dainty fairy necklaces, these glistening strings of pearls ascend radiantly, sinuously, toward the surface. I reach to touch one and the serpentine string sways gently away.

A large patch of lilies with their white and yellow flowers grows at the west end of the lake. The idea of snorkeling through a thick stand of lilies, foot-wide leaves forming a canopy over the water below, seems odd, I suppose. But how can one learn what the patch is like without going in?

Entering the edge of a lily colony is much like walking into shaded woods. Sunlight striking open water becomes muted shade the moment I part two green stems with my hands and enter the lily grove. The water is cooler as well.

Fish in small schools arrive immediately, as lily stems sway in gentle rhythm with waves at the surface.  The mass of plants is not as impenetrable as I had first feared. Guiding myself with outstretched arms, I travel a slow-motion slalom path, turning this way and that to stay within the more open leads through the stem curtains. Both leaf and flower stalks are much longer than needed to reach surface from bottom. This slack makes it easier to push stems aside. It also gives plants the flexibility to safely ride out angry waves that might otherwise rip leavers from stems and stems from roots.

I take a deep breath and dive for the bottom, intending to remain there as long as my air holds out. But bodies prefer to float. No sooner do I reach the lily rhizomes than, against my wishes, I begin floating to the surface. The remedy, I discover, absent a weight belt, is to grab hold of a lily rhizome. I dive again, find one as thick as my arm, and hold on for dear life.

Now anchored, I look up at the surface. Backlit by bright sun, the ceiling lights up into a hundred shades of green. Small pools of water sitting on the upper surface of the leaves appear as green splotches, contrasting with the lighter colored leaves, dark green clouds floating in a grass green sky. Other leaves, in stages of decay, add splotches of amber and yellow and brown.

Random beams of light penetrate the ceiling unhindered through gaps between leaves and, like a dozen tiny spotlights, draw my eye from one highlighted object to another. A young lily leaf, the fresh green of new life yet unfurled. Brown diamond-shaped rhizome scales highlighted against the glistening white of the rhizome body.

A particularly large beam spotlights in brilliant radiance the pièce de résistance. Bathed in the light of center stage, the tender green bud of an unopened lily flower emerges from the tip of an uncoiling stem spiraling out of the bottom’s darkness. Two narrow cracks in the bud’s green envelope emit brilliant slivers of pure white, giving promise of the burst of glory to come when the bud reaches the surface.

No wonder magical powers have been attributed to this plant since medieval times. An ingredient of love potions, the flower must be picked under a full moon, and those who collect it must plug their ears to avoid becoming bewitched by water nymphs. Bewitched indeed. But a body’s scream for oxygen cannot be resisted indefinitely. I hold onto the rhizome to the last second then release my grip and zoom to the surface through a forest of stems.

One sets aside all sense of personal dignity venturing into such places. Emerging with a lily leaf the size of a dinner plate flopped sideways over your head and draped over an ear, swim mask and snorkel tube hopelessly entangled in green stems, quickly sweeps respectability away.

.  .  .

Countless stems populate shallow waters, and a layer of tannish green, I could call in gunk, covers them all. On some plants I touch it is thick like fuzz. Others feel slimy or even fluffy. I’ve also seen it black or brown. None elicited thoughts of beauty. Aquarium keepers know that left unattended, aquarium walls become less clear by the day, as gunk grows from a smudge into a yellow-green-brown layer so thick you can’t see fish through the glass. Gunk to some, it’s known as periphyton to others. (Peri means around and phytom means plant in Greek).

No need to snorkel to see it. On rocks and docks, plant stems and leaves, and sunken tree branches—it’s nearly everywhere in lakes. Mundane and ubiquitous, periphyton is easily overlooked as unimportant. In truth, periphyton is a rich amalgamation of bacteria, algae, fungi, single-celled creatures that creep or swim, myriad tiny animals, and sometimes marl, mucilage, silt, and tiny bits of debris from decaying plants.

Aquatic plants gain no benefit from this blanket on their surfaces. Periphyton sucks up nutrients that would otherwise be available to the host plant, and in some cases obtains nutrients directly from the plant itself. It also screens out as much as 80 percent of the light that would benefit the plant.

Some plants and large algae produce transparent mucilaginous coverings to prevent periphyton from taking hold. I run my fingers along a pondweed leaf. The periphyton layer feels thinner than in other lakes. Nutrient-poor waters can cause that, but in this case, I think it is snails. Windrows of empty shells pave the shore, and live snails cling to plant bodies everywhere. In places they are so numerous I can’t avoid crunching the shells with my step.

Many animals make a living grazing on periphyton. This growth turns even the most austere rock surfaces into bountiful gardens of things to eat for creatures from mayfly nymphs to amphipods, and crayfish to snails, especially snails.

That periphyton attracts snails and other eaters is no surprise. It contains twice the nutrients of other aquatic foods and is more nutritious than the plants themselves. What’s more, it can neither run away nor bite back. Snails and other grazers can remove half the periphyton crop produced in some lakes each day. By eating periphyton, snails keep plant surfaces and aquarium walls clean. When pumpkinseed sunfish feed heavily on snails, periphyton grows lustily and plant growth declines.

. . .

Two pumpkinseeds hover off to one side and below me. One suddenly darts to the bottom, snaps up a snail three-quarters of an inch long, then promptly spits it back to the bottom. These fish are specialized by jaw anatomy to prey on snails. The attacked snail was apparently too large for the fish to handle.

Snails seek cover when sunfish are present. That likely explains why I see so few small ones. Sunfish have a window of opportunity to eat snails when they are small, provided they can find them.

A chill sweeps over me, and I stand, shivering, to get my bearings. A pair of swans with three cygnets float between a lily patch and the shore. One tips herself upside down, submerging neck and head to form a perfectly perpendicular line with the water, tail end pointing skyward the way an Olympic diver in top form appears at the moment of water entry. Now she rights herself and spits out a mouthful of plants onto the water. Cygnets scramble to gulp it down. Over and over again, she and her mate repeat the sequence as insatiable youngsters splash and lunge for the obviously delicious fare, periphyton and all.

I return to the canoe, dry off, and break out lunch, my mind reveling in the wonders of the morning as taste buds savor food. Refreshed, I paddle down the lake to resume snorkeling off a sandy shore. I launch myself and wriggle directly into a dense stand of plants with threadlike stems and leaves, Najas (nigh-us), named for the water nymphs in Roman mythology that give life to a lake.

Now over deeper water, columns of green plants the shape of long bushy squirrel tails appear, soft and pliable to the touch. The bushiness comes from whorls of small leaf stalks, each stalk bearing many pairs of short threadlike leaflets resembling the structure of feathers. This is milfoil, abundant and native to North America (not the invasive Eurasian species). Its lacey fanlike “leaves,” a leaf type common among plants committed to life submerged, hardly seem like leaves at all. A plant with such leaves would quickly dehydrate and die on land.

A turtle emerges into an opening in the milfoil three feet down, turns, paddles slowly toward me, stops, eyes me intently, now disappears behind plants. Within his camouflaged refuge, he moves stealthily to a narrow opening in the plants and pokes the tip of his head through the slit to spy on me once more. Pessimism carries the day. He turns suddenly, thrashes his legs, and disappears into a jungle of green, knocking loose a shower of gray marl that settles slowly to the bottom.  

Plants thin out in deeper water and become taller. Milfoil cylinders reach up from the dark bottom heavenward, like skinny church steeples without the churches. I now enter a gathering of skinny stemmed aquatic plants of a group called “pondweeds.” “Weed.” What an unfortunate and misleading name for these plants. Language matters. Before being seen, before revealing anything about their lives and relationships, they stand condemned. Useless. Nuisance. Undesirable. “Pondweed” is not simply a generic name for aquatic plants, despite its common use that way. Pondweed is also the name of a large and grand family of aquatic plants known more technically as the Potamogetons (Po-ta-mo-gee’-tons) (from Greek, Potamos, river and geiton, neighbor). How different our perception of these plants might be had we retained the Greek root and called it “pond neighbor.” What power the namers-of-things can have over attitudes. (I must note the invasive exotic pondweed species, curly-leaf, so disrupts our lakes it richly deserves to be called a weed with all the negative connotations.)

Again, as before, when I near vegetation, fish come, schools and loners, fish the length of my little finger, fish the size of my hand. One sunny, not three inches long, swims right up to my mask and we stare at each other, eyeball to eyeball. What on earth is he thinking? I could swallow him whole in one gulp. What drives his curiosity? Maybe he is inspecting me for periphyton, judging whether it’s worth his time to look me over for snails, except his gaze is transfixed on my face. Were he to do this to a largemouth bass, he’d be swallowed in an instant. In a few moments he turns and swims lazily away. What has turned off his predator-awareness sense? Has he determined my movements are too clumsy to pose a threat to him, no more dangerous than a submerged log? Two sunfish nip at my ankle and another bites at the shiny metal of my wedding band. I can hear the click of mouth against metal.

A largemouth bass glides into view and mingles with the sunfish. These bass are sunfishes’ main predator. Why don’t the sunnies flee in fear into the surrounding potamogeton forest? They must sense he is not large enough to eat them.

This bass keeps his distance. A skilled predator, he understands the concept of strike-distance as well as I do. No predator can afford to cruise around wasting energy striking out at any prey fish in sight. Bass instinctively understand that strikes are most often successful when the intended victim is no farther than a foot and a half away. Bass that follow the foot-and-a-half rule are deadly, nailing their prey 70 to 80 percent of the time. Is that what’s going through this fish’s mind as we look each other over? Is he trying to determine why my strike distance might be? He swims off into the plants.

As the water deepens I hyperventilate for greater air reserve and dive into an open space among scattered potamogetons. I spot the largest bass I’ve yet encountered. At nearly three pounds, what a catch he’d make. When he appears to lose interest, I swim slowly away then look back. He has followed me. I swim farther and look back again. He’s still there. I maneuver between two large clasping-leaf pondweeds. There he is, still behind and below me. Is he stalking me? Surely he can’t intend to attack. Though when bass pursue prey, the first step is to follow the potential victim. Is his behavior toward me the compulsive instinct of the predator that cannot be resisted, like dogs chasing cars, ancient yearnings too deeply embedded to deny, even when the pursued is not vulnerable? Maybe he likes the cover I provide for him. I once watched a large sunfish hover beneath my canoe, moving to remain in its shade. Or maybe he’s noticed how sunfish attracted to me are the right size for him to eat and he’s using me as a decoy. I feel strangely uneasy.

I see other potamogeton species. One lies on the bottom with leaves in a single plane resembling a fern. Three others have leaves tightly clasping the stem, giving these plants a cylindrical look. 

Now a different pondweed. This one’s broad banana-peel leaves droop like the floppy ears of a lovable rabbit. Potamogeton amplifolius, bread-leaf pondweed (Ampli, large; folius, leaves). A massive stand of broad-leaf appears ahead. The droopy leaves transform the lacy world of milfoils and other petite leaf plants into one of coarse texture, a place of overhanging balconies, of places to rest and hide and ambush. I understand immediately why it came to be called “bass weed” and “muskie weed” by fishermen. This plant, together with the rest of the potamogeton tribe, is the largest source of food for waterfowl. It also harbors food for fish. Broad-leaf is picky about water quality, and is one of the first plants to disappear from a lake when quality declines. That such large colonies thrive here deeply satisfies. The water nymphs tend their garden with loving care.

The bottom slopes sharply away to greater depth, and plants become less crowded. I reach the outer edge of vegetation and look into deep clear water. Long spindly green fingers of clasping-leaf pondweed reach for the surface in a magical world where the laws of physics seem no longer to apply. The plants grow heavenward like unassisted vines, as though gravity has no claim on them. Scattered individuals of the small-leaf species, more spindly yet, suspend themselves motionless. But I perceive with the terrestrial’s mind. Water’s buoyancy and endless air chambers embedded everywhere within these frail bodies only make it seem that gravity sleeps.

Several sunfish schools coalesce and swim down an alley between plants. I follow, like the last float in their parade. They head out over deeper water, so I stop. And, of all things, the fishes stop too, and most of the school swims back toward me, as though wondering what’s the matter? Why have I stopped? They act concerned that I’m okay. Why do they pay any mind to my leaving them? By swimming benignly among them have I unintentionally entered membership in a finny brotherhood? Their attention moves me.

I watch them watch me, then turn to resume my travel paralleling the shore. I stop suddenly and look back, and there they are, following me. I feel like the Pied Piper. I quick-stop again and they nearly bump into me. Underwater slapstick. A Three Stooges routine.

. . .

New periphyton smothers surfaces in a filmy yellow-green shroud. The leaves of the pondweeds become scaffolding for algal filaments to bridge open spaces. I dive. Periphyton blankets the lake bed with a gently undulating layer of tan gauze the texture of cotton candy. Periphyton triumphant. All spring and summer the plants, with the help of grazing snails, have grown faster than periphyton. Now, in late summer, the tide has turned. Many plants are slipping into senescence. With plant growth all but halted, periphyton has finally overcome. Senescent plants become decaying plants, then nonexistent plants, and the living creatures of the periphyton, without substrate, must die and decay as well.

I collect pieces of milfoil, fern pondweed, and water crowfoot and swim to shore to photograph them. As I submerge them in water in a white pan and straighten them out, the water comes alive. Tiny waterfleas, damselfly larvae, seed shrimp, even planaria skitter and slide across the pan to new hiding places. Every one of them a tasty morsel for a minnow, a sunfish, a bass, even tiny walleyes and pike. I have flushed the multitudes from their homes.

. . .

I reach for dry clothes and look at the world I am leaving. Lake water looks to my eyes exactly as it did long ago, but not to my mind. My mind frolics, enveloped by this soft and delicate place of intimacy and shadow, mystery and illusion. Where plants grow as though their architect didn’t believe in gravity, where fish float as if on ethers, like birds riding invisible thermals.

My brain revels in these new exotic dispatches from the eyes. It’s been said “vision” is comprised of one part input from the eyes and four parts from the brain. Like the sunfish peering through my mask, unsure what to make of this strange intruder, my mind now blends the new with its own sense of things.

Swimming among the potamogetons is incomparably more inspiring than sorting out their anatomical differences on a lab table. Their world is vastly different, vastly richer and more interwoven than any I could learn about looking over the side of a canoe. I have experienced them in their place on this earth, and that has made all the difference.

Can one come to love the aquatic plants of a lakeshore, those despicable weeds in the minds of some? Is love a spontaneous, altruistic feeling of affection toward something that has touched one’s emotions? Though it be homely, festooned with periphyton, sometimes crowded but always sublime, having experienced this enchanting place, how can I feel otherwise?

Does it all matter? Essayist Scott Russell Sanders says, “We treat with care what we love, and we love only what we have truly learned to see, with all our senses alert.”

Most people will never enter this enchanted world with snorkel tube and so will never experience the transformation that turns the mundane into magic. Can virtual perception stand in for experiential perception? Oh, how I wish that it could. The vegetated zone of a lake is more than a place to delight the senses. It is a sacred garden. Loss of the garden plucks the pulsating green heart from the lake.

. . .

A loon calls a single note from midlake, a coda in the song of the garden, a sign my adventures have ended for the year. Loons will soon flock up and fly south. Thoreau played a game with the loons of Walden Pond, guessing where they would pop to the surface next. He always lost. Thoreau attributed metaphorical power to loons. Because they could penetrate the surface and dive deeply, they could get closer to the hard bottom of truth than humans. “Seek truth?” asks the loon. “Come beneath the water and find it.”

Author Darby Nelson, Professor Emeritus at Anoka-Ramsey Community College and aquatic ecologist, served three terms as a Minnesota state legislator and is the former board president of Conservation Minnesota. For Love of Lakes was published by Michigan State University Press in 2012. He is also author of For Love of a River: The Minnesota, published by Beaver’s Pond Press in 2019. Please find out more about these books and where to purchase them on his website. Sincere thanks to Darby and his wife, Geri, for granting Agate permission to share this fascinating and beautiful essay. He dedicates Love of Lakes to Geri, his “paddling companion for life.”