I was talking just about that the other day with my wife, and remarked that oceans are large - they can probably eat that exposure without much consequence. But the Allies also dumped those weapons into Baltic Sea, where it now poses a danger to the ecosystem (and consequently, the economy of my country and our neighbours).

On the German Islands in the North Sea there are still employees of the "Kampfmittelräumdienst" - bomb disposal squads walking up and down the coast line looking for stuff that gets washed ashore. Especially problematic are incendiary bombs where the content reacts with air like white phosphorus. People pick them up thinking it to be amber pieces and put them into their pockets and end up with horrible burns in the hospital.