The Black Sea is littered with deadly weapons. But no-one knows how many – or where they are. "When we approach it, we should be quiet, we should be slow – and we should be very accurate," says Vitalii, wiggling his hand in a snake-like motion, as he describes swimming through dark waters towards the explosive devices resting on the sea floor. The tall, softly spoken 31-year-old Ukrainian Navy diver is part of a team of 20 tasked with de-mining the parts of the Black Sea still under Ukraine's