Having exhausted all the exotic possibilities on Earth, high-end hoteliers are now experimenting with the aquatic life.

In Dubai and the Bahamas , whole underwater hotels are under construction. The $500-million underwater Dubai resort, the Hydropolis Hotel, will include 220 bubble-shaped suites, as well as a ballroom and a spa.

The $40-million Bahamas project, built 15 metres deep, off the Bahamian island of Eleuthra , will have rates of nearly $2,000 a night.

In April, Hilton introduced what it says is the first undersea restaurant in the world. Fish can watch you eat their cousins, and the menu is heavy on seafood at the aquarium-style dining room that seats just 14, five metres deep in the Maldives (a series of low-lying islands off southern India ).

Part of a $5-million renovation of the Hilton Maldives Resort & Spa, the restaurant is encased in arching acrylic walls, giving diners a 270-degree view of the marine life all around.