Environmental groups are up in arms about training exercises conducted by the U.S. Navy — not sonar this time, but underwater explosives. The Wild Fish Conservancy and Public Employees for Environmental Responsibility have filed a federal lawsuit against the Navy, saying its practice of training divers to explode dummy mines in Washington State’s Puget Sound poses an unacceptable hazard to salmon, orcas, sea lions, birds, and other wildlife. The National Marine Fisheries Service conducted an environmental review of the practice, and the Navy has made some alterations to lessen its impact, but the groups say more could be done. Pointing to one training exercise that blew up at least 5,000 fish, the groups suggest that the training be conducted in the open ocean instead of shallow harbors and canals. “We are not trying to block Navy demolition exercises,” says PEER’s Adam Draper. “We are simply trying to induce the Navy to train without creating needless carnage.”