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Poseidon Undersea Resort

Where: Fiji

Some 150,000 people have allegedly signed up to be notified once opens for business. The five-star underwater resort in Fiji was scheduled to launch in 2008, but a combination of the global recession and the difficulty of sub-aqua building have led to it still being incomplete five years later. Ambitious projections show an underwater library, golf course, and tennis court, while the website promises future guests the use of a personal submarine.

Insider tip: If you really want to jump the queue, contact Poseidon about booking a wedding in the undersea chapel. Just don’t set a date yet.

Plan Your Trip: Visit

World's Coolest Underwater Lodgings

Undersea hotels represent one of the newest frontiers in hospitality. From Zanzibar to Sweden, beautiful underwater properties with one-of-a-kind views have been popping up around the globe, featuring some of the most unique rooms that travelers can book. Meanwhile, closer to home, many celebrated US aquariums offer sleepovers that aren’t just for kids anymore. Check out our picks for places that allow you to sleep under the sea (or at least pretend that's where you are).

By Rachel B. Doyle