A few years ago I left my office in the Flatiron building at the end of the workday, walked a few blocks down 23rd Street, and arrived at a small apartment where I took off all of my clothes and immersed myself in a sensory deprivation chamber. At the time I was a novice meditator with little experience working with my mind, and I was unsure what to expect. I wasn’t particularly worried I would progressively devolve into a primitive man and then a blob of primordial matter, à la William Hurt’s character in Altered States. But I was concerned about losing it in there.

What familiarity I had with the topic derived from the writings of John C. Lilly, who first conceived and experimented with isolation tanks while working as a neuropsychiatrist for the government at the National Institute of Mental Health in the 1950s. Lilly had earned medical degree from the University of Pennsylvania in 1942, and early in his career was considered a leading researcher in neurophysics and psychiatry. His early isolation tanks sounded like scary contraptions, and things got wonky in the 1960s when he started dosing himself with large quantities of acid and ketamine and immersing himself in the tank for hours on end. Suffice it to say that he subsequently developed some rather crazy theories, dolphins were involved, and the less said the better about the Earth Coincidence Control Office (ECCO) and their intergalactic struggle with the forces of the malevolent Solid State Intelligence (SSI). I nonetheless suspected that the tank could offer a worthwhile experience to me as a meditator, Lilly’s more baroque acid fantasias aside.
My immersion was drug-free and considerably more conventional, but interesting nonetheless. I stepped into a bathtub full of highly salinated water in which my body was buoyant. Both the water and air were body temperature and could scarcely be felt so long as I laid still. The chamber was pitch black and sound proof, so there were no visual or auditory stimuli. For an hour I practiced shamatha with the breath, my only other reference points being my thoughts and internal bodily sensations. It was certainly groundless and a little bit scary but I came through OK. Perhaps the most revelatory part of it all was how much previously unnoticed stress I held in my shoulders.
Recently I’ve considered revisiting the tank. I’m curious about what it might be like now that I have a few more years of meditation experience behind me. Don’t tell the SSI.