Throughout the first season, Eleven did her best to bring back Will. What had to be built in the school's gym to help her communicate with Will?

A sensory deprivation tank, or isolation tank, is a lightless, soundless tank filled with saltwater in which individuals can float. One such tank was present in the underground subsystem of Hawkins National Laboratory. When Eleven entered the tank, her usual sensory experience was inhibited, allowing her inner psychic abilities to be enhanced.

Asked by Vasilii Kulev · Last updated 5 years ago · 8K views · SOURCE