I've seen it suggested elsewhere that he was hoping to get it down on Patrick AFB's runway, but didn't get quite close enough. Looking at the pic in Nige321's post above, the ditching appears to have taken place adjacent to the beach side car park in
the centre of the map here - about half a mile short and with the beach and A1A to cross.
Watched
Discovery launch from KSC from around that spot in September '88 - a bonus was watching a U-2 launch from Patrick a short while before (a U-2 and not a TR-1!).