Heard they had to deliberately sink the Columbian Herk as it drifted into the shipping lanes and posed a hazard. Could just be rumour to make a good story better - also heard the Nav died of lead poisoning.
Of course, there's also Jockey 14 - the AC-130H that crashed off the coast of Somalia in '94 or '95. The USAF made a training tape out of interviews of the surviving crew.
Ditching is not something I'm keen to try in the Mighty Hercules...