December is marked by the arrival of snow in much of America, but in Hawaii it marks the return of the humpback whale. These migrating behemoths move south from their North Pacific homes during the winter months for courtship and calving, and they put on quite a show. Watching males and females alike throwing themselves out of the ocean and into the sunset awes even the saltiest of sailors. Newborn calves riding gently next to their 2-ton mothers will stir you to your core. These gentle giants can be seen from the shore as they make a splash, but there is nothing like having your boat rocking beneath you in the wake of a whale's breach.

Atlantis Majestic Cruises. The 150-foot cruise vessel Majestic bills itself as the smoothest whale-watching tour on Oahu and guarantees a whale sighting. Because of the boat's size—it has three decks—you can choose from indoor or outdoor viewing while listening to Hawaiian music and an onboard naturalist who provides information as you search for the leviathans. Included among the offerings are 2½-hour lunch cruises. Departures are from the historic Aloha Tower Marketplace at Pier 6. Transportation from Waikiki can be arranged. Check-in begins 30 minutes before departure. Arrive early to get a table near a window for the best views while you dine. Aloha Tower Marketplace, 1 Aloha Tower Dr., Pier 6, Downtown, Honolulu, Hawaii, 96813. 800/381–0237; www.atlantisadventures.com. From $69.

Wild Side Specialty Tours. Boasting a marine-biologist/naturalist crew, this company takes you to undisturbed snorkeling areas. Along the way you may see dolphins and turtles. The company promises a sighting of migrating whales year-round on some itineraries. Tours may depart as early as 8 am from Waianae, so it's important to plan ahead. The three-hour deluxe wildlife tour is the most popular option. Waianae Boat Harbor, 85-471 Farrington Hwy., Waianae, Hawaii, 96792. 808/306–7273; www.sailhawaii.com. From $175.