Diving became a lot safer with the introduction of alternate air sources. These devices allow you to share air with your buddy in the event of an out-of-air emergency. The three common alternate air sources are octopus regulators, integrated air sources, and redundant scuba systems.

No matter which option you use, it's important to place it at or near your chest so your buddy can easily locate and retrieve it when needed. Clips are available that hold the air source's mouthpiece secure, but allow your buddy to quickly pull it free when needed.