nightswimming
Etymology
From night + swimming.
nightswimming means Swimming at night. Lexicurio rates it Sui generis — a strength score of 93 out of 100.
Why this word is great
NIGHTSWIMMING — [Noun] The act or practice of swimming during the nighttime. From the English words night (the period of darkness) and swimming (the act of propelling oneself through water). Unlike "nocturnal swimming," which frames the act biologically, or a "moonlight swim," which promises romantic, specific luminescence, nightswimming is a private, terrestrial surrender to the dark. It is the tactile shock of cool, invisible water on sun-warmed skin, the muffled splash and echo in a suburban pool after the last light is turned off, and the unsettling freedom of moving through a liquid void where the bottom has disappeared—a fleeting baptism into the quiet heart of the world.