Another one, not mine, but one I witnessed...
We were playing Prospect Park in Moline, IL. I forget which hole it was (#14 I think?)... My friend drove his Valkyrie towards the basket, but caught a roll on the hillside, and rolled all the way into the lake. To our surprise, it was floating upside down on the water, its edge right at the surface of the water. The wind was fairly light, but ended up pushing the upside-down Valkyrie all the way across the 400 foot lake over the course of us playing the last few holes. About 10 minutes after finishing 18, we were at the edge of the lake, waiting for it to float the last 30 feet or so...then a fisherman lent us his net. Great success!