Ayyy nana taylor and I came up with the same plan for dealing with slashers!
She made one rookie mistake, though: never pick a scientifically significant location for immortal body disposal. It'll get dredged up by a team of wide eyed marine biologists going "gee, how'd THAT get down here?!"
At the very least they'll point it out on their nifty little deep sea cams and it will catch someone's attention eventually.
It's better to choose a less impressive underwater trench if you want someone to genuinely vanish, like, 4th place in depth. And maybe entomb their concrete slab with a placard labeling them as some sort of hazardous waste.













