To reach most hotels you simply fly or drive there, but to get to Jules Undersea Lodge you'll also need scuba gear. Located at the bottom of a lagoon in Key Largo, Fla., the freestanding resort sits at a depth of 21 feet and is monitored 24 hours a day from a nearby "surface control center."



Guests enter the former undersea research laboratory through a moon pool opening at the bottom of the structure. The greater pressure within the hotel prevents it from flooding. Inside, guests find most if not all the comforts of other guesthouses: two bedrooms, a well-stocked kitchen/common room, air conditioning, telephone, hot showers and a full entertainment system. The main attraction, though, are the 42-inch round windows that allow unimpeded views of the ocean environment from the bedrooms and common room.

While two couples at a time typically occupy the hotel, which can sleep as many as six people, those wishing for more privacy can rent the entire hotel for $1,295 per night. And the proprietors will provide a "mer-chef," who will swim down and prepare a gourmet dinner-or, if you prefer, deliver food from a local restaurant. 



While the Jules Undersea Lodge caters to guests who are either scuba certified or have taken a three-hour diving course, future hotels could put the undersea world just an elevator or train ride away. Currently under construction on a private tropical island in Fiji, Poseidon Undersea Resort will transport vacationers via elevator to one of 24 suites 40 feet below the ocean surface. According to the designers, the resort will feature the world's largest and most elegant undersea restaurant and offer attractions such as the ability to pilot a three-person mini-sub in the lagoon or descend 1,000 feet offshore in a 16-passenger submersible. The resort, which plans to open in early 2012, expects to charge an all-inclusive rate of $15,000 per person per week.



Hydropolis, an even more ambitious project under development in Dubai, will feature a submerged train to take guests from a land station to an underwater complex occupying more than one square mile of seafloor and containing 220 suites, various restaurants and even a ballroom. While prices will reportedly be in the $5,000-per-night range, it remains unclear when or whether the oft-delayed resort will be finished.