In my opinion, it's a karma thing...
Just last week, I was diving at a popular beach and I found a dive knife in great condition in the sand in about 15 feet of water. I picked up and carefully stowed it in my sleeve for the rest of the dive.
When I got out, I asked around and was told that So and so from dive shop X had been asking about her knife... she knew that she had lost it.
Later that afternoon, I stopped by Dive Shop X and left it for her. Four days later, when I checked in at the airport, the ticket agent returned my passport to me which I had left on the plane a week earlier.
If I can, I try to return things, partly because the benefit I get from returning them is always greater than the value of the item itself... So, I am still trying to decide what kind of dive knife I should buy.... any suggestions?
Liz