pbr British explorers have found the world's deepest undersea volcanic vents more than three miles under the sea.br ppbr Scientists from the National Oceanography Centre in Southampton made the discovery in the Cayman Trough in the Caribbean using a remote-controlled robot submarine.br ppbr They discovered slender spires made of copper and iron ores.br ppbr The water being pumped out from of the so-called "black smokers" is hot enough to melt lead.br ppbr The area is almost half a mile deeper than has ever been seen before and, with extremely high water pressure, it is tantamount to a "hell on Earth".br ppbr The boiling water that gushes out from deep-sea vents helps to nourish colonies of marine creatures.