"I remember watching a YouTube interview with a military diver. He described how when you’re doing a covert op you spend a lot of time just underwater doing nothing with no lights on until it’s time to move.
He specifically mentioned how he had to get used to having large things bump into him in the pitch black."
Not a bad idea but you might want to avoid the word dumping.
Burial at sea is the more common term.
More likely than not the writer was referring to Hawley Harvey Crippen. Check out the article at www.thehistorypress.co.uk/articles/the-notorious-case-of-dr-crippen/