Being underwater and having a regulator second stage in your mouth makes it pretty much impossible to communicate by talking when you’re scuba diving. Part 3 of out series of lessons from the Ko Tao PADI diving course investigates the easiest and most effective ways to communicate underwater.

Pairing up with another diver is essential to safe scuba diving. By sticking to the buddy system, you have someone making sure you’re ok throughout the dive, giving a second opinion on navigation and the dive plan, and able to assist you in the event of a problem. Accidents are very rare in diving, but when they do occur, the most common contributing factor is that a diver became separated from their buddy or group, and ended up in a situation which they were unable to cope with alone.

So sticking with a buddy is an essential safe diving practice. But how can you communicate underwater with your dive buddy?
Although you can speak through the regulator, the sound becomes muffled, so it’s difficult (if not impossible) to make yourself understood.  So how do we communicate?

For routine / repetitive messages the fastest and easiest to make yourself understood is using hand signals. Irrespective to which country you’re from, where you learned to dive and which diving certification agency you trained with, there are a series of standard diving signals which everyone understands.

Here are some of the most common scuba diving hand signals:

Ok? Ok	Ascend
Problem	Descend
Boat	How much air left?
Slow Down	Out of air! (should never need to use this one!)

Most of the time, this series of diving hand signals are sufficient to articulate whatever it is we need to say. But in some circumstances, communicating a complex message isn’t possible by hand signals.

In this case we’ll need to use an aid. Most seasoned divers carry a simple underwater slate and pencil, so more detailed information can be jotted down and shown to your buddy. You can also buy underwater magnetic boards (similar to ‘Etch-a-Sketch’) which can be reused many times on a single dive – however these are larger and more cumbersome so less popular.

Sound actually travels faster in water than air, so noises can be heard from long distances. As we discussed, speaking underwater is impractical, but that doesn’t mean we can’t make use of sound. Tapping a metallic object (such as a dive knife) against your scuba cylinder is a great way to get other divers attention. Similarly, most dive schools implement a boat recall system of continually revving the boat’s engine in cycles, combined with hitting a metallic object against the ladder which is submerged into the ocean. Both these signals can be easily heard by all divers across the dive site, so it’s an effective way of recalling all divers to the boat.

So that gives you an insight into how we communicate underwater around the Koh Tao diving sites. Check back again soon for part 4 of our series of articles from the Koh Tao open water course, where we’ll investigate what’s included in a typical dive plan.