GPS Mapping by Boat (IMAGE) Umea University Caption Mapping a lake by GPS positioning and depth sounder by boat is very time-consuming, therefore the researchers decided to use a theory driven approach in the study. (low-resolution image) Credit David Seekell Usage Restrictions Feel free to use this photo in the context of this news release. Please give credit to the photographer. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.