Abstract: A system that extends the use of a navigation system which uses radio waves to a an environment which is otherwise inaccessible to radio-based position, location, or navigation services. This system provides beacons which dynamically determine their positions and broadcast data to any number of underwater users. By receiving and processing the beacon data or the signal upon which it is modulated, the user dynamically determines its own position within a geodetically-based time-space coordinate system. Extending externally-generated navigation information to an underwater user need not be limited to the Global Positioning System or its signal structure. Underwater extensions of LORAN, Omega, and other navigation services are also amenable to the technique.