update:
tl;dr: Did the exact opposite of a float tank for about 30 minutes.
apparently we misunderstood each other when booking, I was supposed to be there last week. Also, they misheard my name so the confim email went to greg@grossmier.net (lost an e).
Instead, I laid under a rapidly changing LED light thingy that with your eyes closed basically gives you visuals like if you rub your closed eyes and see those patterns.
Was.... I wouldn't pay for it.
@greg_grossmeier I wish there was a shorter way to imply just how much I am laughing about that.