You did not happen to go across the border to Bosnia did you? Even places that have been cleaned are bordered by places that are mined (villages in the north from my personal experience) meaning that if you are kicking the ball around in a back yard and it goes over the fence, don't go looking for it.

But look on the bright side. There's a chance the ball may come back to you on its own. Very quickly. In many pieces.

Also the sea has all kinds of military garbage

"The southern Adriatic Sea has represented a major dumping area of war residues of both conventional and chemical weapons for almost a hundred years"

http://www.arcgis.com/home/item.html?id=64f53412f4d84603b277...

Lots of areas were used to dump surplus munitions at the end of both world wars. North Sea, Irish Sea[1], Baltic[2], Gulf of Mexico[3], and many other places.

In the case of the Irish Sea, which was the main MoD dump since around 1920, 14,600 tons of Phosgene, and by 1949 the RAF alone had dumped 137,000 tons. It ceased being used in 1973. [1]

In the Baltic fishermen catch upto 3 tons of munitions each year.

BP turned up quite bit of unexploded ordnance while exploring for their now infamous Gulf of Mexico rig.

[1] http://www.telegraph.co.uk/news/uknews/1488371/MoD-dumped-mu...

[2] http://www.spiegel.de/international/europe/world-war-ii-muni...

[3] http://usnews.nbcnews.com/_news/2012/09/28/14141378-world-wa...