Considered the founder of small-boat adventure cruising and ecotourism, with journeys to the Galápagos, South Pacific, Alaska (pictured above), Antarctica, and the Arctic Circle; allied with National Geographic, with top-notch naturalists, and photographers. 800-397-3348, www.expeditions.com
A leader in polar expeditions, offering a variety of Arctic and Antarctic voyages, known for its state-of-the-art ice-breaking ships and adventure options such as kayaking, camping, mountaineering, and zodiac landings. 888-978-5792, www.quarkexpeditions.com
One of the largest adventure travel companies in the world, traveling to all seven continents; marine biologists and naturalists join eight- to 27-day cruises to the Arctic, Antarctica, and West Africa.
For 120 years, this groundbreaking company has been showing passengers Norway’s widely scenic, fiord-filled west coast; voyages to Antarctica, the Arctic, and Greenland are also offered. 866-552-0371, www.hurtigruten.us
A leader in cruises to Ecuador’s Galápagos Islands, using 20-passenger motor yachts; a 16-passenger, custom-built vessel also offers scuba diving in the waters surrounding the lesser visited northern islands.800-633-7972, www.ecoventura.com