Helicopter Sea Combat Squadron THREE (HELSEACOMBATRON 3 or HSC-3) (previously Helicopter Combat Support Squadron THREE (HELSUPPRON 3 or HC-3)), also known as the "Merlins", is a United States Navy multi-role combat helicopter squadron based at Naval Air Station North Island in San Diego, California which operates the Sikorsky MH-60S Knighthawk helicopter to train aircrew and support fleet development on the MH-60S for the Commander Helicopter Sea Combat Wing, U.S. Pacific Fleet.