Ascent rate (9–18 m/min)

Your ascent rate is the speed at which you move toward the surface during a dive. It is a vital safety metric because rising too quickly causes nitrogen bubbles to form in your blood. Most dive computers show this speed in meters per minute. You should generally stay between 9 m/min and 18 m/min.

I saw many students in Koh Tao in 2018 ignore their computer alarms. They often swim too fast because they want to reach the boat quickly. This mistake is dangerous. Always watch your gauge while you ascend. If your computer beeps, slow down immediately so that you do not risk a decompression incident. It is better to arrive late.