Float tanks in the VI
maybe looking for a "sensory deprivation" tank will net you more results.
either way I'd be interested if you find one
Nothing, aside from a guy who used to take LSD and hop in one back in the 50's 😛
probably not too hard to build one, even with temp control for the water etc...
the sound deadening would be the hardest part... you'd have to use a lot of dynomat, or a series of chambers filled with sound deadening insulation; and of course a ton of Epsom salt
crawl into your cistern and have the lid closed...pretty much the same thing!
Isolation tanks used to be popular back in the 80's. We used to take some shrooms or other such hallucinogenics and climb in the tank for an hour or two of trippin. It can be too intense for some though.
try just floating on your back with your eyes closed at a quiet beach, very relaxing.