We lost a nice ski rope, skiing at night one time. After that we got one that glows in the dark.

There's a outboard in the middle of my cove, I saw it fall off a guy's little aluminum boat one day and they never found it, despite having divers out for several hours the next day.

Oh and the prop off my old whaler. Someone forgot a cotter pin.

I recovered an entire lower unit from a friend's boat, too. He hit a shallow, sharp rock a full speed with a 40hp Evinrude outboard. He sheared off the lower unit so cleanly, the prop was UNTOUCHED and they were able to use it on the new lower unit. The cowling came off the engine and hit the driver in the back of the head, though. That engine still runs great, by the way!