Fishermen use GPS to keep up with key spots and it is a great way to share information. I do magazine articles each month for Alabama Outdoor News and Georgia Outdoor News where we take a lake, talk about the patterns bass are on that month and where and how to catch them. Ten spots, with GPS coordinates, are put on a map. Fishermen seem to love that.
You can get relatively inexpensive hand-held GPS units that are amazingly accurate. My first was a Lowrance unit that cost less than $200 and it was about ten years ago. Linda took me to Antarctica on a cruise and I turned the unit on while we were off an island near the Antarctic peninsular. The island and peninsular showed up on the unit!
Try a GPS - I think you will like it.