Proposed in 2006, the proposed underwater hotel for Fiji known as Poseidon Resort Mystery Island has released new designs. Although it is still seeking funding to support the development you can now start saving your pennies for this vacation paradise. They estimate it will cost $30,000/couple for a week.
Marble Caves, Chile. This palace is located in the town of Sintra. It has gargoyles, grottos, and this spiral staircase. The estate is so large it even has two small lakes, a chapel, and servant's quarters.
If I see this image pinned once more as an "underwater hotel" in Dubai I might freak out. I was just here 2 months ago. It is a huge aquarium in the Atlantis hotel on the Palm in Dubai. This is on the basement level where shopping and restaurants are located. Very cool place, but not anywhere near being an "underwater hotel".
Unimaginably cool. A little over five years ago, Conrad Maldives Rangali Island opened the very first undersea restaurant. To celebrate their anniversary, the restaurant offered guests the chance to not only eat under the sea, but sleep under it as well. The 12-seat restaurant, which sits 16 feet below sea level of the Indian Ocean, was converted into a private bedroom suite for two, complete with a private champagne dinner and breakfast in bed.