Sensory deprivation tanks aka flotation tanks are probably best known to the general populace by the part they played in the film Altered States – where they are used, in conjunction with hallucinogenic drugs by psychology professor Edward Jessup (played by William Hurt) to access extraordinary, eventually frightening states of consciousness and then physical metamorphoses. While the latter has yet to be documented, the former is undeniable and modern ceremonial magicians are suggesting their use in experiments to empower such work. Here’re some recent articles on the subject and a guide to the flotation tank nearest you!
and while you’re reading these, you can listen to this:
thanks to Soror hypatia for the tip