The divers communicate by gestures, indicating if there is danger nearby, or if someone is going through some problem. There is no way to communicate with the mobile, no matter how resistant it is to water, since this environment absorbs the signals and makes it impossible to transmit them.
What it is possible to do is transmit sound waves, animals do it, and anyone can verify how talking underwater can hear “something” several meters away, even if nothing of what is transmitted is understood.
The fact is that there is a company that has managed to create an application that transmits data underwater using sound waves.
It is about AquaApp, an open source UW Mobile Intelligence Lab experiment that uses mobile phone speakers to create high-frequency audio signals and send data. The receiver (another mobile) will capture these sound signals and transform them into data to identify what the sender was saying.
To use it, it is only necessary to download the app and put a waterproof case so that the phone resists. The app will take care of identifying and correcting fluctuations in signal intensity, caused both by movement caused by humans, as well as by waves and nearby objects.
In tests they have shown that they are capable of exchanging data reliably over 100 meters, at a low speed, but enough to send messages that can save lives, synchronize jobs and much more.
