Humans evolved to walk on land and deal with nearby objects. They later used boats, rode horses, and traveled in carriages. The development of engines led to high-speed travel in cars, trains, and aircraft. Humans also started diving underwater using various gas mixtures. They explored most of the world and landed on the moon. These activities stretched human physiology to the limits, and depended on artificial habitats or survival apparatus. The environments also stretched human perceptual systems, which had not evolved to cope with all possibilities. Perceptual adaptation to some sensory transformations is possible, but we cannot replace total losses of sensory information. This entry describes how various environments affect visual, auditory, and vestibular perceptions.