[silentbicycle]

I've been in an isolation tank, too. The most noteworthy aspect was how, after a time* , my sense of balance / spatial orientation had gotten enough repetitive input that it checked out. At the same time, my body had gotten used to being supported fully by the water, and I could feel muscles in my back, shoulders, etc. relaxing that I didn't know I had. (Sometimes the same thing happens when I do zazen, though that usually focuses more on letting my mind give up on its chattering.)

A flotation tank is a bit different than what's described in the article - if you move, you feel waves in the water, hear splashes echo, etc.

All of this focusing on hallucinations seems kind of odd. People hallucinate all the time, they just rationalize it as misreading signs and whatnot. Big deal.

* I'm guessing half an hour, but the isolation unsurprisingly made it seem far longer. Isolation without control would be terrifying.