A Hypothermia Table is germane to these discussions. Note that the table was designed for sea kayakers. In colder conditions without flotation, somewhere between loss of dexterity and unconsciousness, you drown. This couple was fortunate they fell overboard in the Gulf Stream and were spotted by a couple professionals.
Ah man, went fishin' and all I caught was a couple idiots -- can't eat 'em, can't throw 'em back.