I think this is in Taiwan.
In Pingtung, Taiwan (near the south end of the island) there is the National Museum of Marine Biology and Aquarium. A lot of the museum is “underwater” or in tunnels with the aquariums being around them. (I suspect this is that museum, or some another one, because of the label/diagrams in the back).
When I visited this place last year, I was told that people can pay to sleepover in these tunnels. If you ever get a chance to go to Taiwan, I would suggest a visit to the museum. =)