To have easy access to a full menu of water activities, book into the Hyatt Key West Resort, which can arrange everything from a jet ski to a yacht.
Visit the Mel Fisher Treasure Hunting Museum where you'll see the riches discovered on sunken ships by Fisher, who was a well-known undersea treasure-hunter. The institution also offers a weeklong workshop on shipwreck conservation and commercial salvaging techniques with treasure-hunting dives along the Atocha Trail.
Feel like an old salt yourself by lunching at Capt. Tony's Saloon, the celebrity hangout where Jimmy Buffet got his start. It's said to be the oldest bar in Key West and where Hemingway did much of his drinking when it was Sloppy Joe's.
Spend the afternoon zooming around the coast of Key West aboard a ski jet on the Ultimate Water Tour with stops for adrenaline-pumping playtime in the Gulf of Mexico and Atlantic Ocean, an unclose look at mangrove nature and historic points around the island. The 90-minute guided tour ends with a cold beer at the dock. Each jet ski can accommodate two, including one child over age four.
Wind up the day with an intimate 2.5-hour Wine & Sunset Cruise on a Danger Charter out of the Westin Marina. Relax as you watch the sun set from the deck of an historic Key West Schooner where fine wines and upscale beers are free flowing and served with tasty appetizers.