Naturally constrained environments like bays and lakes are frequently used for water sports activities. While the sound of motorized vessels is rather well understood, non-motorized activities have received less investigation. Ten water sports activities (swimming backstroke, breaststroke, butterfly, and freestyle; snorkelling with fins; kicking a boogie board with fins; paddling with alternating or simultaneous arms while lying on a surfboard; scuba-diving; kayaking and jumping into the water) were recorded in a controlled yet even more constrained environment: an Olympic-sized pool. Activities that occurred at the surface involved repeatedly piercing the surface and hence creating the bubble clouds which were the strongest sound generators. Received levels were 110–131 dB re 1μPa (10–16,000 Hz) for all of the activities at the closest point of approach (1 m). All activities produced a characteristic spectro-temporal pattern in all the quantities measured (sound pressure, particle displacement, velocity, and acceleration) by which they could be identified. Applicability of the results to security monitoring of pools, performance assessments of professional or competitive swimmers, and studies of the distances at which humans may be detectable by marine animals in the sea will be discussed.