Scuba divers remembered words better underwater if they'd learned them underwater

In a 1975 experiment, divers memorised word lists either on a beach or several metres underwater, then were tested for recall in both environments. Recall was consistently better when the test environment matched the one where the words were first learned. It's one of the clearest demonstrations that memory encodes its surroundings along with the content itself.

— Duncan Godden and Alan Baddeley, Context-dependent memory in two natural environments: on land and underwater — British Journal of Psychology, 1975