Underwater navigation represents a particular challenge for divers and is often a risk factor that should not be underestimated. A reliable system for position determination could mean an increase in safety and could support the special forces and first responders in emergency organizations (fire brigade water service, military divers, water rescue, etc.). This is precisely what the Scubanav exploratory project aims to do by creating the basis for developing such a GNSS-based underwater navigation system. It uses surface buoys equipped with a GPS receiver to determine their position and emit GPS-like underwater signals, which the underwater receivers use to determine their position. Scubanav is developing the technological prerequisites to evaluate the implementation of such an underwater navigation system. A needs-based technology design is created through the participatory involvement of different user groups (scuba divers, fire brigade divers, military divers, and professional divers).