The closest most passengers get to the sea is a few decks above it. Oh, the irony of it. The ships here encourage cruisers to dive in and stay wet

Safari Explorer
Line: American Safari Cruises
Passengers: 36
Itineraries: Alaska, Hawaii
This Lilliputian yacht's Hawaiian itinerary finds the most sheltered waters off the island chain so that passengers can make use of the kayaks, water skis, snorkeling equipment, and even small sailboats found onboard. (One favorite excursion is a snorkel around a nearly submerged volcanic crater off Maui.) While passengers dry out, Hawaii-based naturalists lecture on local culture, fauna, and boatmanship. The Safari Explorer was relaunched earlier this year on the heels of a $10 million makeover that added a wine library for tastings, and suites with whirlpool tubs and balconies (888-862-8881; amsafari.com; eight-day Alaska Inside Passage trip from $5,995).

SeaDream II
Line: SeaDream Yacht Club
Passengers: 110
Itineraries: Caribbean, Mediterranean, Transatlantic
What sets the SeaDream II apart from most small ships is the retractable marina at the stern, laden with snorkeling gear, Zodiacs for water-skiing, Sunfish sailboats, personal watercraft, and other complimentary water toys. This equipment sees more use in the warmer waters of the Caribbean, but you'll likely have it all to yourself on a Mediterranean sailing. After a day on the water, guests retire to cabins with marble-lined bathrooms that have multijet massaging showers and Bulgari bath products, 24-hour room service, and flat-screen TVs with DVD players (800-707-4911; seadreamyachtclub.com; seven-night Mediterranean trip from $6,000).

Star Clipper
Line: Star Clippers
Passengers: 170
Itineraries: Asia, Mediterranean
Like to sail but don't have your own boat? The Star Clipper encourages passengers to help raise the sails, climb the mast, and even steer the ship. Novices steady themselves on the teak deck as they are taught to tie nautical knots or splice a line, and can visit the bridge to watch the captain plot the day's course. A highlight for the boat set is the stop in Falmouth, Antigua, a nexus for Caribbean yachting. Sailing isn't the only aqua adventure available during this cruise: On the itineraries that sail around Thailand, passengers can go sportfishing in Surin Islands National Park and enjoy some of the finest diving in Asia in Similan Islands National Marine Park, accessible only by sea (800-442-0551; starclippers.com; five-night eastern Mediterranean cruise from $1,626).