Most travel journalists have a favorite “best kept secret.” Mine is hidden in plain view. Whenever you fly between the United States and Europe, it’s there on the in-flight map: a roughly circular lump of land stranded in the North Atlantic approximately midway between the two continents. During daytime flights you might even catch glimpses of it below: black volcanic mountains, green tundra, white-water rivers, vast glaciers. Iceland.

The secret is this: When you cross the Atlantic on Icelandair, you can stop over in Iceland for up to seven days without any addition to the airfare. Wherever you are ultimately headed, a few days spent on this amazing island will be a dramatic contrast.

Flights touch down at Keflavik International Airport (KEF), where arriving passengers are channeled through the duty-free shop. Whatever your tipple, it is well worth stocking up here. Due to heavy taxation on alcohol, Iceland is the land of the $10 glass of beer, the $50 bottle of unexceptional wine, and the $100 bottle of Jack Daniels.

Once outside, it is immediately apparent that you have arrived at one of the wildest spots on the planet. Keflavik is situated on the Reykjanes peninsula: You may as well have landed on the moon (indeed, this is where the NASA astronauts were trained prior to their lunar missions). The road from the airport wends between raw lava fields interspersed with steaming sulphur springs. First-timers invariably stare out of the windows in awe.

The capital, Reykjavik, is about an hour away. It is a collection of mostly red-roofed buildings clustered on a peninsula, and feels more like a fishing village than a European capital city — and fishing remains a vital part of life here. To experience the essence of Icelandic life, head out to sea.

At Reykjavik Harbor, we board the 44-foot vessel Gestur. Our boat was dwarfed by the robust trawlers of Iceland’s commercial fleet, which are designed to cope with some of the world’s most treacherous conditions. The Gestur is relatively stable, though for the benefit of those of us without sea legs this voyage was dependent on the weather. Happily, there was only a slight swell today, so we maneuvered away from the quay and chugged out into open water Soon we were rocking through the peaks and troughs of the moody Atlantic. With fishing rods readied, we cast our lines into the deep. These are productive waters that, until the 1970s, were bitterly contested between Britain and Iceland in what became known as the “Cod Wars.”

Cod is what we managed to hook that day, though other fish regularly caught on these expeditions include haddock, catfish, and, if you’re very lucky, giant halibut. Our catches were grilled in the galley, and as we returned to port we enjoyed the fruits of our labor for supper — the freshest possible seafood.

For all the comforts of the boat, deep-sea angling can be a tough, muscular activity. If you prefer your fishingwith a little more finesse, Iceland’s rivers provide some of the best flyfishing in the world, for Atlantic salmon, brown trout and Arctic char. Depending on time and inclination, you can enjoy several idyllic days on remote riverbanks in the farthest-flung corners of the island, or you can spend a couple of hours on the tangle of streams collectively known as Ellidaar within Reykjavik’s city limits. Here, in sight of the city center, there is a good chance of hooking the migratory salmon as they begin their journey to the spawning grounds upstream.

Until the advent of the modern road network, venturing into Iceland’s interior was a journey every bit as arduous for humans as the salmons’ epic migration. The early Vikings sought fourlegged assistance, and imported the first horses to the island in the late ninth century. Over the past thousand years, these horses have evolved into a tough, stocky breed ideally suited to the challenging terrain.

At Laxnes Horse Farm, we took to the saddle and rode for two hours along mountain trails to the beautiful Trollafoss waterfall (the name refers to the trolls, that, according to legend, infestthe island). In addition to the usually walking, cantering and galloping, Icelandic horses have a unique gait known as “tolt” — a rhythmic form of locomotion that provides for a remarkably smooth ride over the craggy terrain.

In winter, even the horses struggle to get around, but help is on hand from another four-legged friend. As in other northern lands, dogsledding is a practical means of transport during the coldest months. Even when the seasonal snows have melted, several significant year-round icecaps remain. On one of these, Myrdalsjokull, within day-trip reach of Reykjavik, you can get a taste of mushing. If you like, you can learn to control a team of hardy Greenland sled dogs, though be warned that the dogs only understand Icelandic. Or you can just sit back in the sled watching the stunning scenery as the dogs and musher do all the work.

Further along the southern coast is the island’s largest icecap, Vatnajokull, a vast white wilderness that covers an area of 3,200 square miles. For Icelanders, it is one huge playground. Jeep safaris are a popular means of visiting the heart of this great dome of ice, with its mountains and glacial lakes.

But if you really want to experience this frozen environment up close and personal, the best option is a guided snowmobile tour. As you cut smooth tracks across the virgin snow, you gain some measure of the sheer scale of Vatnajokull. And when you stop and turn off the engine, the silence is total.

At the end of your time in Iceland, there are two worthwhile diversions prior to catching your flight from Keflavik. The first is Iceland’s most famous attraction, the Blue Lagoon, which despite its romantic name, is actually the effluent pool of a geothermal power plant. In winter, especially, it is an incredible experience. You strip to your bathing suit in the changing rooms, then brave sub-zero temperatures as you dash across frosty ground to reach the sanctuary of the warm, sulphurous, outdoor pool.

Pungent steam swirls across the surface. You scoop up handfuls of white silica mud to smear over your skin — its healing properties are so well documented that it is officially prescribed for patients with skin conditions. All too soon, it is time to leave, and you must psyche yourself up to briefly exposing your flesh to the bitter air as you run back to the changing rooms.

Near the end of my Iceland stopover, there was time for one last memorable adventure. At the docks at Keflavik, I embarked on the 90-passenger ship Moby Dick and headed once again into the rocky, white-capped waters of the Atlantic, where I entered one of the world’s richest habitats for marine mammals; the sea around the Reykjanes peninsula is renowned for sightings of whales and dolphins. The Moby Dick promises a 97 percent success rate, and sure enough, we soon found a pod of minke whales. They surfaced regularly, spouting, then slipped beneath the surface.

On some voyages, blue whales, orcas, fin whales, and several dolphin species are spotted. For us, there was one final surprise in store. As we headed landward, a humpback whale breached, falling back into the water with a tremendous splash. For several minutes we watched its heavyweight acrobatics, and then, finally, it dove back whence it came, flicking its flukes out of the water as a parting gesture. Iceland, it seems, was saying goodbye — and beckoning us to return.

TAKE NOTE

Full details of the Iceland stopover program are available from Icelandair ( http://www.icelandair.com ). Deep-sea angling trips are offered by Reykjavik Whale Watching (tel 354 555 3565, http://www.elding.is ) from June to August. For more information about fly-fishing rivers, contact the Angling Club of Reykjavik (tel 354 568 6050, http://www.svfr.is ). Salmon season runs from June 1 to Sept. 30.

A seven-hour excursion to Laxnes Horse Farm (tel 354 568 6050, http://www.laxnes.is ) including transport to and from your Reykjavik hotel, a two-hour horse ride and lunch, costs $125. Hour-long dog-sledding trips are available with Dog Steam Tours ( http://www.dogsledding.is tel 3,54 487 7747). The cost, including transfers from Reykjavik, is $295 ($125 if you provide your own transportation to the start point, but the last five miles are sometimes impassable by car — check in advance).

Glacier Jeeps ( http://www.glacierjeeps.is tel 3,54 478 1000) runs a range of jeep and snowmobile tours daily May-October. A two-hour excursion costs $236 per person (on a two-person snowmobile; there’s a supplement of $75 if you want to ride single). A three-hour jeep safari costs $127.

The Moby Dick is operated by the Keflavik-based Dolphin & Whale Spotting Company ( http://www.dolphin.is ) from May-September. A three-hour trip costs $50 per person. If you don’t see any whales or dolphins you will be offered another voyage free of charge.