Underwater Hotels were hotels that operated underwater. They provided a new experience for people.
The first underwater habitats were constructed in the 1960s. Jacques Cousteau, who invented scuba gear, built many of these. Most were open pressure. Some were closed pressure. There were even some that were both. Most underwater habitats during the Cold War were outposts designed to diving, underwater construction, studying aquatic life, training dolphins, military research and espionage, maintenance, construction of oil rigs, climate research, tourism, aquaculture, and training for astronauts. They were built on the surface and placed into the sea by submersibles. They were still connected to the surface for power and communications. As time went on, underwater habitats became less dependent on the surface. They started providing accommodations for people. This gave rise to underwater hotels.
Tech Level: 10
The first underwater hotel to be built was the Jules Underwater Lodge in the Florida Keys. It had five rooms and could only accommodate six passengers. People had to scuba dive to get there. The Poseidon Undersea Resort went many step ahead of the Jules Underwater Lodge. Built in Fiji in 2014, it was connected to the surface by tunnels. Each suite had a view of the coral reef. They also had bathtubs and sinks. Finally, they had exterior lights and fish-feeders. There was also a rotating restaurant. Insulation was incorporated into the transparent windows to keep heat from escaping. The Hydropolis Hotel in Dubai was built with a land station connected to the main hotel via tramway. Other underwater hotels were also built. But during World War III, the military needed underwater habitats that could last for weeks. This led to underwater bases.