Dolphins! A pod of spinners, breaking about 25 yards off my bow. It's illegal to approach them, but I couldn't help it if they came to me. I pulled on my mask and fins and slid into the blue briny. I hung there in the deep for a while beside my kayak, waiting, watching. Slowly, a few of the dolphins came in for a closer look, then whirled through the mirrored ceiling into the air. Soon they were all around, and I could hear their sonar squeaks, watch them spin. It was like being in the midst of recess at dolphin kindergarten.

That's the greatest appeal of kayaking in Hawaii—or in any tropical waters: You can just roll off your open kayak and swim or snorkel, then clamber back in. And there's wonderful kayaking on all the islands, but the best, to my mind, is along the Big Island's Kona Coast, with its fine snorkeling, lava tubes, and caves to explore, and miles of roadless and storied shoreline.

Recently I joined Aloha Kayak for a guided paddle led by Iwa Tolleson, a native Hawaiian. We launched at Keauhou Harbor and headed south, along a shore with no trace of development. The waves exploded white against the eroded black cliffs; the hillsides above were wet and green. We passed the battlefield of Kuamo'o, where in 1819 the Hawaiian monarchists defeated the traditionalists with their priests and ancient kapus. The old religion—and 300 warriors—died here; we saw the black stone terraces that marked the burials.

After a while we turned into a calm cove; in a minute we were all off the kayaks and snorkeling. The water was about 15 feet deep. I swam off to explore the submerged lava tubes where parrot fish and Moorish idols browsed. A sea turtle floated nearby. The other paddlers climbed up the steep black cliff and took turns diving into the incoming swells (a 45-foot drop that didn't interest me). We played for an hour or so, then climbed into the kayaks and paddled back to Keauhou Bay. Our outing ended on a historic note as we ate lunch near the sacred spring where King Kamehameha III was born in 1814.

Explorers have all the fun—carving paths through uncharted regions and braving hidden dangers in search of the unknown. By the time we Johnny-come-latelies show up, the trail has already been blazed, the flags are all planted, and the T-shirt shops are doing a brisk business. We're left to imagine what it was like to be the first to venture into a new frontier.

I was trying to do just that while kayaking along the pine-and fir-lined banks of the Columbia River near Astoria, Ore. Lewis and Clark's Corps of Discovery arrived on these shores in November of 1805 following an ambitious 4,000-mile survey across the western United States. Images of buckskin-clad men gathered on a beach, cheering and high-fiving each other, popped into my head. The trailblazers then hunkered down for a few soggy months at what is now Fort Clatsop National Memorial before making their return trip.

"An authentic Lewis and Clark winter" is how a Fort Clatsop ranger had described the cool, misty rain that now hung in the air. Putting in on a small, wooded tributary east of town, I'd set off to follow in the wake of the Corps. Fleece stood in for buckskin. A lone seagull shot across the pale gray sky as if it were late for a date. The men of the corps had hunted along these riverbanks for elk to keep themselves alive. I had a Power Bar to tide me over until dinner.

A trio of ring-necked ducks sat floating in place around one bend. I cruised over to check out the scene. The black-and-white threesome slipped into a small cove, thick with reeds, with me on their tail. It was clearly a setup. Wet, spaghetti-like reeds dripped off my paddle and the rudder of the boat threatened to get all tangled up below. The feathered fiends ducked back out with ease as I fumbled to escape. Sacagawea, somewhere, was rolling her eyes.

Once I was free, the gentle current took over and the kayak bobbed along for another half-mile to an old wooden railroad trestle. A few well-placed strokes took me under the squat pilings and out to the mighty Columbia. The river, perhaps sensing a new arrival, took to bouncing the kayak around a bit.

A weather-beaten, seemingly abandoned fishing boat sat about a mile offshore. Upon my approach, a large black dog peered down at me and said hello in a tigerlike growl. Frantic paddling ensued when this mouthful of fangs with legs got ready to dive in and give chase.

When Cujo was far enough behind, coast mode kicked in. The damp haze thickened and rain began making rings on the water. Gazing west toward where the river and the sea converged, I considered those first explorers and my own pseudoexpedition. Tricky ducks and angry guard dogs aside, it seemed that trying to retrace someone else's footsteps was not as big a deal as making some of my own.

S H O P   T A L K Before you can rent a traditional closed-deck sea kayak without a guide, most outfitters require that you have taken an introductory course. Without the class, you can only paddle the sit-on-top kayak, the equivalent of a bike with training wheels. Traditional sea kayaks, which consist of a skirt attached to the shell, are less stable than the sit-on-tops. Simply reaching for a fallen cap in the water may cause your vessel to tip. Unlike scuba diving's certification program that's overseen by a governing body, the sea kayaking requirement has become a trend among outfitters who are concerned about safety. "The industry realized that if they let inexperienced people go out in a closed-deck kayak, they were putting them at risk," says Kate McClain, the owner of Blue Waters Kayaking in Inverness, Calif. "If someone falls out of a boat and doesn't know how to get back in, they can suffer from hypothermia." A typical course runs about $80 to $100 and lasts a full day, offering you the survival skills for encountering wind, fog, waves, currents, cold water, and boat traffic. Your instructor will cover the basics of the sport from the differences between sea and river kayaks to how to read tide tables to proper paddling techniques. Kayaking requires minimal upper-body strength, but it helps to be in good overall physical condition. The heart of every course is the rescue that allows you to safely reenter a boat. If you'll be swimming in cold water, it's recommended that you wear a shirt (nylon or other synthetic) under a wet suit, which the outfitter usually provides. By the end of the day you'll be able to paddle safely—and you'll be the holder of a little card that proves you don't require training wheels.

The full moon has long had a pull on Earth, affecting tides, werewolves, stockbrokers, poets, and, as it turns out, business at Sea Trek, a sea kayak outfitter in Marin County, Calif. Of the more than 30 guided trips offered by Sea Trek, the Full Moon Paddle on San Francisco Bay is the most popular. "People think we're a nocturnal company," says Bob Licht, Sea Trek's owner and founder. "The magic of being on the bay under a full moon makes this trip so popular. It's quiet and the moon reflects on the water like a pearl."

Last fall, my husband and I signed up for one of these trips. Our adventure began at the Ocean Kayaking Center at Schoonmaker Point in Sausalito. Before the sun set, three guides spent 45 minutes explaining the basics of kayaking to our group of 14. As the sun sank behind the Golden Gate, we launched our two-person kayaks onto Richardson Bay. We paddled into an orange and pink sky and explored the shallows that skirt the waterfront, passing time until the moon rose. We wove through boat docks, where seals poked their heads above water, and through a houseboat community, where televisions reflected blue on windows.

As night fell, Mount Tamalpais blackened into a dark silhouette. The guides passed around chocolate chip cookies. A giant sphere, the moon rose slowly, poking its head above Angel Island and finally lighting the entire sky. Under the lambent light, we admired the bay from a perspective inconceivable to a landlubber. We floated in a world that was peacefully vacant, like a dream without cars, buildings, people, or noise. We could see the hurly-burly of the real world—cars inching across the Bay Bridge, twinkling lights outlining San Francisco—but from a quiet distance. On our return, we passed pricey restaurants, such as Scoma's and Ondine, where floor-to-ceiling windows overlooked the water. Behind glass, diners sipped wine and enjoyed their view. We became a part of their conversation as they pointed at us and waved.

Our trip, on a warm, clear evening when the bay was smooth, was nearly perfect. Licht says these optimal conditions are typical in the spring and fall, but he adds that the trip is still fun when it's foggy. "People want a clear sky and bright moon," he says, "but if it's hazy, the moon is like a Japanese painting." We were intrigued and knew we'd be back.

I wanted to gaze at the forest-clad shoreline of San Juan, the second largest island in Washington's archipelago, the San Juans, from a single kayak. But no local outfit would take me out in a single. They're less stable than double kayaks and the prospect of a client capsizing in the gelid water is a liability concern. So, I chose San Juan Safaris because they were the friendliest outfitter on the 20-mile-long island and they boasted naturalists as guides.

At Roche Harbor on the isle's north end, I met my group, eager to glide far out on Haro Strait. I was matched up with Russell, a man who promised to be my ideological opposite—a software engineer for big oil in Houston. But except for a couple of quirks (his camera, my piloting), we got along. It was his first time kayaking, so I took the helm, which in a kayak is in back working the rudder. To go left, you push on the left foot pedal and vice versa. Simple. If steering is all you do. Add paddling, conversing, scouting wildlife, and my piloting goes to hell. I'd push on the left pedal to go right, then overcorrect only to lose more ground—or sea, as it were. For the first half hour, I apologized profusely to Russell, then decided this was no way to spend the next three hours.

There was too much to see. Nature lovers flock to the San Juans for their clean wilderness and teeming wildlife. When I wasn't inside my head trying to coordinate left, right, dip that paddle, I saw tide pools brimming with a rich stew of sea stars, anemones, sculpins, sea lettuce. I saw pretty red jellyfish float by and a Steller's sea lion. Birds charted course overhead, including a kingfisher and cormorants that looked as if they were doing wind sprints before takeoff. We didn't see the big attraction, the orcas that migrate through in search of a salmon dinner, but we spotted many harbor seals. Russell wanted to photograph every last one—with a disposable Kodak—"to show my wife." Each time a seal poked its head through the glassy strait, Russell pulled out the disposable and aimed, mostly into the sun. The seals, often indistinguishable from bladders of bull kelp, invariably vanished before Russell clicked.

I spotted an eagle in a Douglas fir and was pleased. Russell, who had never seen a bald eagle, was apoplectic. He swiveled—with camera—in such haste we might have capsized, but for my, at last, fancy paddle work. As we glided back toward Roche Harbor, only the guide and I saw the great blue heron taking flight like a prehistoric leftover. I didn't tell Russell. He had wasted enough film.

We were shoving marshmallows onto roasting sticks when the howl of a wolf drifted across camp. Then another, and another, until it seemed a pack was singing a canon. We rushed toward the beach, hoping to catch sight of them, but the wolves were hidden deep in the trees. No one was too disappointed. We already had watched orcas swim Frederick Sound and gray whales breach. We had hiked through soft muskeg and seen bald eagles fish. Tucked tight into kayaks, we had skimmed across glassy waters and over the canopy of an immense kelp forest. And this was only one day of seven spent paddling a maze of remote, lonesome islands that are strung along Alaska's Inside Passage.

Our trip had started in Petersburg, Alaska, where nine of us—seven guests and two guides—boarded a boat to spend three days climbing in and out of kayaks, exploring the surroundings of Le Conte, Alaska's southernmost tidewater glacier. On the best of these days, we paddled eight miles to the glacier, up an inlet of opaque water choked with icebergs. The floating sculptures took the shape of airplanes, dogs, fish. One was the Sydney Opera House, another a Degas dancer. One nerve-fraying mile was spent bumping our kayaks through huge chunks of ice. When we reached the calving river of ice that poured from the mountains, we watched in respectful silence. That night, back in the bay outside our camp, icebergs the size of 18-wheelers melted until they crumbled apart. The sound was exactly that of thunder.

After three days we piled into floatplanes and flew north to Big Creek (where the wolves howled), along the pink fireweed-lined banks of Frederick Sound. Mornings were spent paddling and whale watching, afternoons tide pooling. We spent one day hiking upstream where we cheered for salmon making gravity-defying attempts to leap tumbling waterfalls.

On our last night, we shimmied into our boats for a final paddle. Two miles offshore we pointed the kayaks toward snowy peaks that were catching the slipping sun. The water lapped quietly at the boats. We heard a breaching whale. But mostly we sat and watched the sun turn the sky the colors of rainbow sherbet, and none of us wanted to go home.