Massachusetts State Police divers delve into the often-freezing Mystic River searching for bombs that could blow up LNG tanker ships calling on the Distrigas import terminal in Everett, Massachusetts. ?We provide security for the tankers when they come in,? said Tom Ryan, Massachusetts State Police trooper. While Ryan declined to provide details, the feats of the force?s dive team are outlined in a confidential report written by the Maine Department of Public Security on LNG shipments into Boston. The dive team inspects the area around the wharf at the Distrigas facility and the shallow area of the Mystic River through which the LNG ships pass. They look for bombs that would have to be the size of a small passenger car and as powerful as an antiship missile to penetrate the double hull of an LNG ship. It would be difficult for terrorists to conceal an antiship missile onshore since it is so big that they would have to move it into firing position on a trailer. Divers face significant hardships, say those familiar with scuba conditions in the area. This includes swimming in frigid waters, said Scott Salman, a spokesperson for the Boston Fire Department. ?It?s dark?it?s black under there except for their lights,? said Robert Granatz, a diver who is secretary of the Massachusetts Institute of Technology Scuba Club, which has hosted talks by a state police diver assigned to the LNG ship detail. State police explained to him how divers swim under the 1,000-foot-long ships when they are in shallow water to inspect the hulls.