Objective. To evaluate and compare the efficacy of commercially available earplugs in preventing water intrusion in healthy individuals. Study Design. Experimental study. Setting. Tertiary care medical center. Subjects and Methods. Ten subjects (20 ears) were assessed. After insertion of the earplugs, subjects underwent 3 standardized head-wetting protocols, including (1) surface swimming for 10 minutes, which entailed no head submersion and moderate splashing; (2) head submersion at a 90-cm depth for 20 seconds with their head upright; and (3) head submersion at a 90-cm depth with head tilted 90 degrees left and then tilted 90 degrees right for 10 seconds on each side to apply vertical pressure. Color change of a wetness indicator was used to determine water intrusion after each protocol. The same protocol was repeated for all 9 earplugs. Results. Water intrusion was observed in 44%, 67%, and 88% of ears after surface swimming, horizontal submersion, and vertical submersion, respectively. The results revealed a significant difference in the waterproofing qualities of the various types of earplugs. The soft silicone type (Pillow Soft) earplug had the lowest rate of water penetration during all 3 protocols (P <.001). The difference between the most effective earplugs, Pillow Soft and Aquaseal, were only significant during the horizontal submersion protocol (P = .008). Conclusion. Water intrusion occurred even with the use of earplugs. The intrusion was more significant with horizontal or vertical head submersion. The soft silicone Pillow Soft earplug was the most effective earplug for preventing water intrusion in surface swimming. © American Academy of Otolaryngology - Head and Neck Surgery Foundation 2012.