Saturday night (Sunday Morning) at about 12 midnight we were heading north on the Intercoastal Waterway after having dinner at a resturaunt in Clearwater Beach. Just past the Dunedin Causeway Bridge we spot a boat in front of us going in circles. After shinning the spot light on the boat we see it is a mid size fishing cat with a channel marker lodged in between the sponsons with the number 22 showing on the triangular red sign........no one was on board. As we watched the boat turn circles running at about half throttle we notified Coast Guard and scanned the water for bodies while keeping the light on the boat to alert other vessels. I have to tell you the uneasy feeling in your stomach seeing the boat running in circles with no one on board and trying to find a body or bodies in the black water in the pitch balck night. After trying to come up with a recovery plan on how the tides were running and the winds so we could begin some type of search for a body (bodies), a boat pulls to our side and says he picked up the (1) person and he is on the nearby island with some pretty bad facial injuries. He was lucky, very lucky !!!!! Wear your lanyards people !!!! Dave