Neutral Buoyancy Pool for Astronaut Training

A neutral buoyancy pool is a pool of water in which neutral buoyancy is used to train astronauts for the difficult task of working outside a spacecraft in a weightless environment. Some of these pools contain full-scale mock-ups of ISS modules and other spacecraft.

Flat-Earthers discovered videos of astronauts in a pool of water, and they jumped to the conclusion that it is how they faked videos of astronauts in space. In reality, these are videos of astronauts in a neutral buoyancy pool, in training for their upcoming mission to space.