The Navy plans to increase ocean warfare exercises, conduct more sonar tests and expand coastal training areas by hundreds of square miles - activities that could harass, injure or disturb the habitats of hundreds of thousands of marine mammals, federal records show. The Navy is seeking federal permits to broaden an existing range off the Pacific Northwest and dramatically expand exercises and sonar use in the Gulf of Alaska. The Navy's plans have ignited a debate with environmental groups that say the service underestimates the long-term impact of its activities and fails to restrict training sufficiently in marine sanctuaries and other areas where it is likely to affect sensitive species. The plans to expand training off the Pacific Northwest, where the service's exercise areas reach into the Olympic Coast National Marine Sanctuary, have drawn about 3,500 public comments, most in opposition. Critics of the Navy's plans point to its use of new sonar systems that can disrupt marine mammals' brain function and behavior, noting that even brief disorientation or other temporary" effects can have serious consequences, such as changes in reproductive activity. Among the most serious concerns is the potential for whales to strand themselves on beaches: Since 2000, there have been at least four instances in which mass strandings of whales have been associated with the Navy's sonar use, federal records show.