From the atolls of the Pacific to the Thames Estuary, shipwrecks of World War Two litter the oceans. After seventy years rust is starting to take its toll, breaching steel hulls and sending cargoes of munitions, chemicals and oil into the environment.

For decades governments have turned a blind eye to the risk, anxious to avoid responsibility for ships sunk in foreign waters. However, as the number of pollution incidents rises it's becoming vital for expertise in underwater salvage to be pooled in a worldwide effort to identify and remediate the most dangerous wrecks.

Tom Heap investigates the latest salvage techniques and asks if the cancellation of funding for coastguard rescue tugs could add to the risk of future wrecks in British waters.