Eighty-two cotton, foam, and solid core stock and custom earplugs were evaluated objectively for water absorption and water penetration characteristics in order to determine their efficacy for control of water-borne infection in ears having open middle ear cavities. Cotton plugs, even when saturated with petroleum jelly, had poor consistency in resisting even minimal water pressure. Polymeric foam plugs, especially when saturated with petroleum jelly, appeared to inhibit water flow in conditions approximating actual ear protection use. No plugs evaluated, including custom elastomeric solid core plugs, inhibited water penetration in conditions approximating shallow surface dives. A clinical protocol for evaluation of potential earplugs for patient use is proposed on the basis of this study.