Aldous Huxley's account of a typical psychedelic trip, from Heaven and Hell, makes me think of a scuba expedition:
"The typical mescalin or lysergic acid experience begins with perceptions of coloured, moving, living geometrical forms. In time, pure geometry becomes concrete, and the visionary perceives, not patterns, but patterned things, such as carpets, carvings, mosaics. These give place to vast and complicated buildings, in the midst of landscapes, which change continuously, passing from richness to more intensely coloured richness, from grandeur to deepening grandeur. Heroic figures, of the kind that Blake called 'The Seraphim,' may make their appearance, alone or in multitudes. Fabulous animals move across the scene. Everything is novel and amazing. Almost never does the visionary see anything that reminds him of his own past. He is not remembering scenes, persons, or objects, and he is not inventing them; he is looking on at a new creation."
People appear larger underwater, like Blake's Seraphim. Also, anything that disrupts your ordinary pattern of breathing -- yogic exercises, chanting, scuba diving -- increases your overall receptiveness. Other thoughts that come to me while reading Huxley in Maui -- tourist resort islands resemble the Other Worlds of comparative mythology, which may bear on why there are so many kistch shiny things for sale here.