ALASKA Explore the untamed wilderness on Safari Quest, Abercrombie & Kent's 120-foot yacht. Sail from Juneau to Glacier Bay National Park, then get in a kayak and scout for puffins, sea lions, and black bears. Back on board, continue along the 500-mile Inside Passage, where you'll go ashore for guided nature hikes and a soak in a natural hot spring. 800/554-7016; www.abercrombiekent.com; eight-day cruise from $5,895 per person, double; June through August.
AMAZON Cruising is the only way to see the world's most powerful river—and most unusual plant and animal life. Sign up with International Expeditions and set sail from the lush Andean mountain town of Iquitos, Peru. From there, pink dolphins escort the ship as it sails past tiny villages to the source of the Amazon, the Río Marañón and the Río Ucayali. 800/633-4734; www.internationalexpeditions.com; nine-day cruise from $2,198, double; year-round.
ANTARCTICA Hapag-Lloyd's 365-foot-long Bremen starts its expedition in southern Chile, then sails to the South Shetland Islands, where passengers ring in the New Year surrounded by elephant seals and chinstrap and jackass penguins. You'll set foot on the Antarctic Continent the first day of 2007 and pass through the eight-mile Le Maire Canal to hike Pleneau and Danco Islands. 800/782-3924; www.hapag-lloyd.com; 21-day cruises from $10,573 per person, double; December 19 to January 9.
NORWEGIAN FJORDS Water carved the deep, dramatic fjords of western Norway. To explore their cracks and crevasses—unreachable by land—book a passage on one of Fjord Travel's small vessels. Between the icy inlets, you'll find emerald-green vertical slopes, fields swathed in pale yellow wildflowers, and tiny hidden villages. 47/5513-1310; www.fjordtravel.no; three-day cruises from $832 per person, double.