Most borders are imaginary. Drive from Connecticut to New York, and a sign tells you of the change. Otherwise, you'd never know. There are some places in the world, though, where the lines are not imaginary.

SCUBA divers can see where North America ends and Europe begins by hopping from Cathedral Ledge in Iceland and taking a plunge. With more than 300 feet of visibility, Silfra is among the world's premier dive sites. Don a dry suit to handle the cold water, and you can straddle Europe and North America.

Come to Iceland prepared. While DIVE.IS, Iceland's dive center, does offer snorkeling and other low-impact opportunities, trained divers will see more. If you have taken the Professional Association of Diving Instructors (PADI) course, you will be ready to experience the blue waters of this volcanic country at a greater depth. The water tends to be brisk, usually around 2°C (36°F). A wetsuit will not be sufficient to keep you warm, so take a course in dry suit use before boarding the Iceland Air flight.

Once you have seen where one hemisphere ends and the other begins, the underwater tour is far from over. Keep enough air in your tanks to explore caves and tunnels that have taken centuries to form. Shrouded in water from melting glaciers, you'll explore a part of the world that requires skill as well as training. The more you know, the farther you'll go! Since there are few fish living in the continental crack, DIVE.IS offers several other dive sites, particularly the geothermal chimney of Strýtan.

Don't spend your entire trip to Iceland below the surface. While the aquatic attractions will try to dominate your attention, make some time to enjoy the palpable luxury of the Blue Lagoon. Located about an hour from Reykjavik, the rich blue waters are heated naturally, and buckets of white silica mud are available for ad hoc skin treatments. A more formal spa is located on the premises, with a talented staff to knead the tension of days of diving from your muscles. Spend a few nights at the spa's hotel to unwind before heading back to the airport.

Iceland is remote, rendering much of what the country offers little-known. Mix excitement and pampering with deep, coldwater diving and the shallow, therapeutic waters of the Blue Lagoon. If you have time, dash into Reykjavik for a quick dinner at the Seabaron, down at the harbor. Start your meal with the best lobster soup on any continent, and try the whale. You won't regret it.

DIVE.IS

Tom Johansmeyer

6/23/08