Undersea attractions; past, present and future

First we'll visit Israel, where Red Sea tourism in the 90's gave rise to a number of underwater attractions, including the Red Sea Star undersea restaurant:As well as this submerged observatory in a harbor, where tourists can watch ships arriving and departing as well as admire the reef fish:
This spa in the Maldives is, like the other attractions listed so far, in fairly shallow water and exposed at all times to the surface atmosphere via a stairwell:The Maldives seems to be a popular location for such attractions as it's also home to the Ithaa Undersea Restaurant, disappointingly shallow but with an enormous hemicylindrical acrylic enclosure:The upcoming Poseidon Undersea Resort will, by contrast, be situated 40 feet or so below the surface, nearly as far as some research habitats:If you're richer than the king of popes, the same company responsible for the Poseidon Resort is also selling extras of that disc-shaped pod at either end of the resort as a standalone undersea home: