Teetering on the edge of a 2,000m trench off the island of Eleuthera, the resort intends to use the splendours of the marine world to attract its upmarket clientele.
Poseidon is the brainchild of the underwater systems engineer Bruce Jones who, inspired as a boy by the diver Jacques Cousteau, has long chased the dream of underwater living.
Construction work on his project could begin as early as next February, provided he can acquire the necessary permits and satisfy the Bahamian authorities that his complex poses no threat to the fragile Caribbean environment.
Mr Jones, who has also been developing luxury submarines for the super-rich, says there will be no shortage of entertainment for his guests. Visitors will descend via an escalator to one of 22 hermetically sealed cabins, each equipped with their own private coral reef garden where guests can operate their own fish feeders. As well as the region's famous groupers, holidaymakers will be able to marvel from the comfort of their own whirlpool bath at passing squadrons of eagle rays, spiny lobsters and patrolling reef sharks.
The operators say they can guarantee the wildlife will remain safely on the outside. A high-tech carbon fibre door opens outward to maintain the unit's watertight integrity, while the whole complex will be built using a steel frame in which are set special three-inch-thick acrylic window sections.
There will be a visiting celebrity programme and regular guest lecturers are planned. Diving lessons and expeditions will be available on-site and a "swim with the dolphins" programme may be implemented. Excursions on a deep diving submarine are also likely, as is a revolving restaurant.
"We have been working on the capability and engineering for the past three years and now we're at the permit stage, which we hope to get in January," said Mr Jones, 49, president of US Submarines Inc. "It will be the most unique hotel property in the world. There is no other where you can spend a dry night underwater in a spectacular natural coral reef setting."
The jewel in Mr Jones' underwater crown will be the resort's two-room, $20,000-a-night penthouse suite, which will be "hung" over the side of the aquatic shelf. It will be accessible only by submarine. The new resort differs from existing underwater destinations such as the Jules Undersea Lodge off Key Largo in that guests will not have to get wet at any stage (apart from in the whirlpool bath). Visitors to the Florida submarine hotel have to don wet suits and dive down to reach it.
Indeed, Mr Jones faces his stiffest competition from Dubai, where architect Joachim Hauser's ultra-luxurious Hydropolis is planned to be built off the Gulf state's Jumeirah coast. The area already hosts the world's first seven-star hotel, the Burj al-Arab and The Palm, a vast man-made island in the shape of a palm tree.
Other idiosyncratic destinations include the Ice Hotel, near Kiruna in Sweden, which is rebuilt every year from 10,000 tons of ice harvested from the Torne River, and the International Space Station, whose third private visitor, Gregory Olsen, returned to earth this month after 10 days in orbit. The price of his jaunt was reported to be £12m.