Deep Communications

By Dennis M. Pulley

One if by land, two if by sea. Remember this one from your American history lessons in school? Since early man, communication has been an intricate part of our world. How else would we know what each other thought or needed? But with so many different languages used around the world, how can we communicate without using the same language? Early Native American tribes figured this out by developing a standard sign language to communicate between themselves when they met. Since the underwater environment is not conducive to the human voice, scuba divers have also adapted and modified the way they communicate while submerged. There are a number of ways that divers can converse underwater and here are just a few.


Slates, like the IST Underwater Slate works well when you have short messages to send or ask, but they don’t work well with extended sentences. Many dive buddies will have a list of questions or commands prewritten on their slates, so when diving all they need to do is point to a line and solicit a response from their buddy. Some of the newer slates are erasable with a simple move of a button so you can use it, erase it, and then your buddy can respond and erase again. Slates also work extremely well for plotting navigation courses that may involve square or triangle patterns. has a wide variety of scuba diving slates.

Communication Systems

Underwater communication systems are effective when you need or wish to carry on a complete conversation. However, they tend to be expensive and cumbersome for the average diver. Even with these systems there can be some limitations to communicating. carries underwater communication devices like the Aquatec Scub-Alert, that is a horn that works above and below the surface.

Hand Signals

Divers typically converse using hand signals. For many years, deaf individuals have used the hand alphabet and other signals to communicate, and underwater communication is based in part on these formats. During your entry-level training, you learned many of the basic signals that you use on each and every dive, such as “let’s go up,” “let’s go down,” “look at me” and so on. You started using many of these signals from the very first pool session and continued using them on all of your open water training dives. On the other hand, there were quite a few that you did not use until later in your training. You would use these if you became involved in a buddy aid situation such as “out of air,” “need air” or some other emergency signal.

Customized signals may be developed just between two buddies or by dive guides at resort locations. These signals can stand for things such as types of marine life or items from a checklist like “how much air is left?” “which direction?” or “it’s time to go up.” While these signals work well to communicate between the two individuals, they may cause a great deal of confusion when diving with others. When developing hand signals, try to remember to keep them simple and obvious as to the intention. Additionally, when you dive with a different buddy, you need to remember to discuss all signals that you may use during the dive, including customized and emergency signals.

You should review all of the signals every time you complete your scuba update—especially emergency skill signals that you do not normally use.

Dennis Pulley is Director of Training for Scuba Schools International.