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Underwater Communication

Effective communication underwater is crucial throughout a dive to keep a dive group together and to ensure everyone is safe, comfortable and still has plenty of air. Dive leaders will communicate their instructions and intentions to other divers, and will often point out and name many marine life species to a dive group so that everyone knows what amazing creatures they are seeing. However, for obvious reasons communication underwater has to be slightly adapted to communication on land. Firstly, we are unable to speak whilst diving because of our regulator and the limited frequency and amplitude of our voices. Another problem is that water actually increases the transmission of acoustic sound due to its density and elasticity meaning sound waves hit both our ear drums at such a speed, the time difference between right and left (or vice versa) is too small for our brains to determine its direction.

Therefore, the easiest and simplest way to communicate whilst diving is by using hand signals. These are easily learnt and understood within the diving community to convey essential messages whilst underwater. From okay, to not okay, asking and responding to air, instructions to ascend or descent, these can immediately be both sent and received at the flick of the wrist. Most dive professionals will also have home grown signals specific to their style and environment, so keep an eye out and listen to the dive briefing on every dive!


Hand signals are adequate for diving, as good buddies and dive groups stay within visual distance of each other, are attentive to others actions, and are recreationally in very safe conditions. However, how can underwater communication be more effective and improved, and what new technologies are being developed?

Our main source of land-based communication is through radio waves, water prevents the propagation and transmission of radio waves unless at very low frequencies, which then limits the power of data transmission and communication. Submarines can use extremely low-frequency radio waves at shallow depths to receive communication (but not transmit), however this is not very applicable to divers who wish to communicate to one another on a dive. To develop more effective underwater communications systems, science looked to nature and found that by harnessing the use of acoustic sound waves as whales and dolphins do, we can begin to send and receive data over greater distances and to greater depths. Special communication systems called hydrophones have now been developed that have the power to convert speech into an ultrasound wave that is emitted in high-frequency vibrations too acute for the human ear. These ultrasounds travel through the water very effectively and are detected and decoded by another diver’s receiver which converts it back into sound. This system clearly has many benefits for recreational divers in buddy teams, but even more so for high-risk tech diving and commercial diving where divers are able to communicate clearly with both each other and any surface support


This technology is great for safety, and there are already products in development to allow simplistic communication through buddy devices that don’t rely on voice communications. So although many divers may not feel the need for open voice communication channels underwater, an additional ‘buddy bracelet’ may become common in recreational diving in the future and allow instant communication at the touch of a button. As the technology advances further, researchers hope to make vast improvements to tsunami detection, pollution monitoring and offshore oil and natural gas exploration.

DART II System Schematic


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