I don’t think you actually believe that the bottom of the ocean is a good place to keep nuclear waste.

You would probably agree with me—and most other people—that a nuclear power plant, the was caught throwing their waste into the ocean, would be an environmental disaster. The US navy doing the same thing is also an environmental disaster.

Presumably the reactors in submarines are commanded to scram when the sub is in trouble.

So the reactor is a high corrosion resistant stainless vessel in non-critical state at the bottom of many tens (hundreds?) of metres of ocean.

All told, that doesn't seem an entirely unreasonable place for it. Even if it was critical, in the active state before the sub sank, it'd probably just heat water for a decade or too before it eventually cools down.

Even if it suffered a meltdown, that's not ideal, but I'm not gonna lose any sleep over it.

Do you really think that?

We are dealing now with barrels of DDT dropped in deep water off the Californian coast