A method and apparatus for measuring depth of waterways and elevation of land features through autonomous consolidation of GPS device data acquired from a plurality of mobile platforms is disclosed. The GPS device data may then be processed and compared to published reference data. A data recorder and a wireless transmission system comprise an onboard unit, which serves to interface with the GPS device for collecting, recording and transmitting data. The onboard device also provides an apparatus for collecting other georeferenced data from multiple mobile platforms, and serves as a node on a two-way meshed communication network.