Purpose: To describe a method for customizing scuba diving mouthpieces, to examine their usability, and to assess divers' satisfaction with their use. Materials and Methods: A rational method for fabricating custom-made mouthpieces for scuba diving was developed. Twenty scuba divers agreed to use a custom-made mouthpiece for at least 4 weeks. After mouthpiece use, participants completed an 11-item questionnaire. Results: Custom-made mouthpieces had significantly lower scores for all items on the questionnaire except uncomfortable sensation, indicating that they were more comfortable than ready-made mouthpieces. Conclusion: It can be concluded that these novel custom-made mouthpieces for scuba diving offer greater comfort than ready-made mouthpieces.