Small-picture summary: SLBMs (submarine-launched ballistic missiles) powered by UDMH and NTO (nitrogen tetroxide, N2O4) were a bad engineering decision. Submarines have a long history of "minor" leaks. Ditto liquid-fueled rockets. And NTO and water will instantly react, at room temperature, producing very toxic gasses, very corrosive acids, and a whole lotta heat...

Big-picture summary: Naval disasters involving gunpowder almost certainly predate the Grand Duchy of Moscow gaining access to the sea, 500+ years ago, under Ivan the Great. Alfred Nobel figured out how to make nitroglycerine "safe-ish enough to actually be worth the risk" 150+ years ago. Since Nobel, clever chemists have cooked up all sorts of really cool & deadly dangerous things for modern militaries to use in weapons. Which of those things are just too dangerous & unstable to actually be worth the risk is a body of knowledge which is always growing - generally one disaster at a time.

> K-219's full complement of nuclear weapons was lost along with the vessel.

I looked for more elaboration on this point but didn’t see anything:

Presumably, they don’t just shrug and say “oh well so much for those nukes” when a loss like this happens, but I’m curious about what recovery of nuclear warheads from 18k feet on the ocean floor involves.

Anyone have any details?

At the time of K-219's sinking, I don't believe the Soviet Union had any Deep Submergence Vehicles (DSVs) capable of going that deep, but they already had the Mir class of DSV in development in Finland, and they were delivered a year later in 1987. The Mir class are supposedly strictly civilian (maybe that's true, maybe not. shrug) They also ordered two military versions of the Mir, the Konsul-class, but those weren't completed until after the fall of the Soviet Union (one in 1999, the other in 2009.)

Any of these could visit the wreck at least in principle, but recover the warheads? That probably depends on the condition of the wreck. If the warheads were thrown clear they might be easier to recover, but harder to find. If the warheads are buried in the wreck, they might be nearly impossible to recover without cutting up the wreck, for which you'd probably need more heavy duty equipment than these DSVs.

Somewhat related, the Kursk sank with nuclear weapons and was cut in half and partially raised to recover them. But that was a very shallow wreck, just 108 meters. The salvage company Russia hired for the job made a neat documentary about it: https://www.youtube.com/watch?v=uQJ6IMREvz8

The US alone has lost three nuclear weapons which have never been recovered [0].

If you search Broken Arrow you’ll find several lists of past incidents and recovery operations.

[0] https://www.bbc.com/future/article/20220804-the-lost-nuclear...

Those three are lost and never found. There are more that have been found but not recovered, including two in the USS Scorpion wreck.

By minor dejavu, K-129 might have been lost to similar cause in 1968. This is the one the Glomar Explorer tried to recover. Is K-912 next?

https://en.wikipedia.org/wiki/Soviet_submarine_K-129_(1960)#...

Nothing of what you read in this article… ever happened.