University of Washington: With a new app, smart devices can have GPS underwater. “…a team at the University of Washington has developed the first underwater 3D-positioning app for smart devices. When at least three divers are within about 98 feet (30 meters) of each other, their devices’ existing speakers and microphones contact each other, and the app tracks each user’s location relative to the leader. This range can extend with more divers, if each is within 98 feet of another diver.”