"The ocean is blue because all the other pigments are absorbed. So after a certain distance down everything thing becomes a monotone blue color, unless you have some other light source.
The freaky part is if a diver gets cut underwater the blood looks black, like ink. All the red has long since been absorbed so there’s no wavelengths left to show you a red color when you bleed."
"Once you get to a certain depth your buoyancy changes and you actually start get pulled down instead of floating up"
"94% of the Earth's oceans are just pitch black darkness."
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/