Here is an interesting map of the United States.
If you zoom in, you can see where ordnance, exposives and UXOs have been dumped off the coast.
This link takes you to a document that lists the locations and other details of all British sea dumping activities around the British Isles ( includes explosives, chemicals and radioactive materials). http://www.mod.uk/NR/rdonlyres/5750E...y_sea_dump.pdf
I have also scanned the relevant page that lists the explosive dump sites.
I was involved in a deep sea dump in the South China Sea in the early 1980's. A quantity of surplus munitions was taken from the Ammunition Sub-Depot in Hong Kong and dumped from an LSL ( Landing Ship Logistic) en route to re-supply the Garrison in Brunei.
any live or dug ordnance. small arms ammunition etc in my posts have been dealt with accordingly