Poseidon Undersea Resort

Giving the phrase "Under the sea" a whole new meaning, the Poseidon Undersea Resort ($15,000 and up) lets you rest underneath the waves in a room made mostly of acrylic glass. Located in Fiji, the resort offers guests private plane transport from a Fijian airport to the Poseidon Mystery Island, where they'll enjoy a week's stay — including two nights in the underwater hotel, with a three-passenger Triton 1000 submarine at their disposal. With a coral reef to explore, beach bungalows for above-sea level accommodations, an underwater library, wedding chapel, restaurants, and more, it's an out-of-this-world experience just 40 feet below the surface.