Excellent account, and I second the recommendation to check out the film Altered States.
Reading your experience, I was reminded of my own from a year or two ago. I took my wife to a spa for her birthday and we discovered they had "sensory depravation rooms" which sounded intriguing as we'd both been meaning to try this for a while now.
Rather than a proper float tank, it was a little closet with a salt water baby pool and pool float. They suggested getting naked and sitting on the cushion and let the experience take you away (or some such).
The only problem was that because it was not a tank, and I was floating on the cushion in the tiny pool, It was basically spinning me around in a circle for 30+ minutes. There must have been a little current in there as well.
Adding to the atmosphere, there was a big palm tree in the room. and when I'd spin around a certain point, the leaves would brush my face. Not quite sensory deprivation. More like induced jungle fever !
My wife emerged from the room totally freaked out saying how it was too weird. I didn't mind so much but couldn't really get into an altered state. More of a fever dream.
Perhaps next time we will go for the real deal.
I'll definitely check out that film! You made me laugh out loud. 😂 What an experience that must've been for you! You guys should try the real thing. Thanks for your comment!