The present invention provides a prophylactic for the ear during activities in and around water or other liquid medium where the ear is subject to infection and barotraumas. It has an outer ear section that fits tight in a user's outer ear and a watertight downwardly extending flexible protrusion that extends into the outer part of the ear canal. A non-collapsing, flexible sleeve with a hollow interior is concentrically positioned within the outer ear section and flexible protrusion. A diaphragm with elastic and water-resistant properties is attached across one end of the sleeve with watertight sealing means. An optional protuberance and/or lanyard may be attached to the outer ear section to assist in prompt invention removal after use, and an external barrier is optional where sudden impact can occur. For water depths below thirty-three feet, the diaphragm should be positioned near or within the flexible protrusion portion of the device.