When I was in Singapore the beaches were littered with left over shells and grenades from WWII. Singapore was moving the sand to places they wanted to build up via a conveyor belt. every so often a ordinance would go off and shut the conveyor down. Being stupid kids who weren't smart enough to be afraid of old grenades, we used to pick them up a throw them into the water. Found mortar shells lying on the beach and threw them into the waves too. Even tho we knew the conveyor was shut down at least once a day, we still played with the left over stuff.
A couple of times a year there are stories about them finding old bombs and other explosives all over the WWII theater, they still have to be careful digging. War is messy.