Rebreather (CCR — Closed Circuit)

A rebreather is a device that lets you breathe the same gas repeatedly. It works by scrubbing carbon dioxide from your exhaled breath before you inhale again. Most divers use Closed Circuit Rebreathers (CCR) for technical exploration or deep wreck dives because they provide a constant oxygen level. While open circuit tanks lose most air to bubbles, a CCR uses very little gas during a 90 m dive. This efficiency allows for much longer bottom times at depth.

Always monitor your oxygen sensors closely. I saw a diver in Koh Tao in 2018 nearly pass out because his scrubber was exhausted. You must track your CO2 levels constantly. Never trust a single sensor reading during a dive.