This may be a dumb question, but why were they tossed into the ocean? Was it because there was no alternative? Or they just wanted them away from potential users of them?
Where else should they have dumped this stuff? That's not meant to be a glib response. It was (and perhaps still is) a serious quandary. Should they have buried these munitions in a field somewhere? In mine shafts? In a remote section of the Alps or Pyrenees? I'd imagine that all of these alternatives would have placed the weapons in closer proximity to humans and civilization, with an accordingly greater risk of catastrophe, at a similar ecological cost.
Consider, in addition: 1) that the weapons were unstable and rapidly degrading, which meant time was not on anyone's side; 2) a third World War seemed not just possible, but perhaps probable, especially as tensions mounted between the Soviets and the Western allies. Very quickly after WW2, the United States realized it did not have the manpower to repel a Soviet land invasion in Europe; in fact, it was outnumbered and outgunned by a significant margin. So the US and its allies very much perceived themselves to be in a race against the clock.
In retrospect, it's east to wring our hands about how these weapons were disposed of. But there were very few choices available, all of them onerous. Given the choice back then, i.e., "Do I want this stuff in the ocean, in the groundwater, or under Soviet control?" policy makers found the ocean to be the least of three evils.
Of course, the best thing to have done would have been to disassemble the munitions and render their contents chemically inert. The infrastructure, specialized labor force, resources, and time to do this were not on hand.
Interesting. I had thought of "We may have to fight another war" but not that it would be too hard to dig a very big hole and bury them under a mile of concrete. (Do with them whatever we do with nuclear waste - granted we didn't have much nuclear waste in 1945)
We should also note that a lot of these weapons -- particularly, the ones seized from the Nazis -- were advanced beyond the technical understanding of the generals who'd seized them.
These bombs and rockets, including their chemical propellants, oxidizers, and payloads, were designed by the world's top rocket scientists, in an era where perhaps a few dozen of those people even existed. Disposing of these things safely and securely would have been a bit like disposing of some alien death ray that turned up in the Arctic permafrost.
Add to this the fact that most of Europe was a bombed-out husk in the aftermath of the war. We're talking entire countries reduced to Third World status. We're talking nonexistent transportation infrastructure. Civil unrest. The threat of riots, uprisings, and invasion on all sides. Factories and assembly plants blown to rubble. Millions of the Continent's best, brightest, and most capable workers annihilated or driven off. Most of the Continent's brain trust being frantically courted by either side of the emerging Cold War battle lines. Total chaos, more or less.
Even getting our hands on enough cement to bury the weapons might have been difficult, given resource and time constraints.
You've got a box full of agonizing death. It's unstable. Doing anything to neutralize it will be both hideously expensive and risky. Over there is, well, the ocean. Your move.
Basically the allied powers had just conquered Nazi Germany and no one was 100% sure that victory was forever. Now imagine a "Werewolf" movement re-capturing a chemical weapons arsenal.
Therefore better to just get rid of the stuff ASAP.
