Here are 20 common scuba diving hand signals. This guide is not intended as a comprehensive dictionary to all scuba diving hand signals, but simply an overview of some of the most commonly used underwater hand signs. You will notice that I have purposefully omitted hand signals to communicate tank pressure. I have omitted these signals because divers use such a variety of signals to communicate tank pressure that to state a "standard" signal would be more confusing than helpful. Be sure to review how you will communicate tank pressure with you dive buddies before your dives.
The "Okay" Signal
The first hand signal that most scuba divers learn is the "Okay" hand signal. The "Okay" signal is made by joining the thumb and index fingers to form a loop, and extending the third, fourth, and fifth fingers. This signal can be used as both a question and a response. The "Okay" signal is a "demand-response" signal, meaning that if one diver asks another diver if he is okay, he must respond with either an "Okay" signal or the communication that something is wrong. The "Okay" hand signal should not be confused with the "Thumbs-up" signal, which in scuba diving means "end the dive."