We examine the relative role of bone conduction and tympanic conduction in underwater localization and detection by humans. Basically, we placed divers underwater and covered up various parts of the skull and outer ear with neoprene foam (an insulator of sound) and measured thresholds and localization accuracy. Sound conduction through the ear canal (tympanic conduction) appears to play only a minor role in the detection of sounds 1000 Hz and higher. Yet conduction through the canal appears to be very important for localization.