Communicating under water can be quite difficult. Wouldn't it be so much easier if you could just text your dive buddies when you found a cool new cave to explore, or when you were panicking because your oxygen was running out?
That's precisely what UTC was thinking too, which is why they invented the two-way digital text messaging service. The underwater SMS device is mounted onto the user's arm and allows for communication not only with the rest of the underwater team, but with those on boats above or waiting on land.
It's called the UDI which stands for Underwater Digital Interface.