STOLEN - Guard your equipment

I was out a local lake to practice diving. All went very well, to a point. I had my wet suit and full scuba gear with me. The tank was new and worked great. I even got a new full face mask. I was practicing counting of fish since the local fish and game ask for volunteers to count fish in the local rivers. The area that I was doing my work was remote or so I thought. The only other person in the area was in a boat out on the lake and I had a small row boat that I had taken to a remote shore line. At one point of my dive I came up to take a break and noticed that a fish depth finder I had with me was gone. The only person that could of taken it was the other boater which had now disappeared. As soon as I got back I reported the incident to the local forest ranger's office. I will be checking my homeowners insurance policy to see if the depth finder was covered. I already checked my auto insurance, since I tow the boat with it car, and it might be covered under that policy instead. I guess I am lucky I had auto and not Motorcycle Insurance. Let's hope I am not completely out of the $300.00 depth finder.