The U.S. Navy is seeking to renew permits to conduct sonar and explosive exercises off the Washington, Oregon and California coasts, raising concerns among marine mammal advocates.

The training area stretches from the inland waters of Puget Sound to the northern coast of California. The area is home to endangered whales such as orcas, humpback and blue, as well as seals, sea lions and dolphins.

The Navy says it need to carries out the exercises to maintain and train combat-ready naval forces.

The Navy's current five-year permit expires in 2015. It has issued a draft report outlining potential environmental impacts as it seeks to expand exercises.

Public meetings have been held in Washington, and are scheduled for Oregon, California and Alaska.