The US Navy says dolphins and sea lions will stand guard this year at a submarine base to detect any underwater swimmers who might approach the base on Hood Canal.The US Navy is keeping security details secret, but the environmental impact statement for the project said there would be fewer than 20 animals kept in heated enclosures when not on patrol in Washington state. Marine mammals have been used as guards for years at another Trident submarine base at King's Bay, Georgia. Navy spokesman Tom LaPuzza in San Diego told the Kitsap Sun that Atlantic bottlenose dolphins and California sea lions are ready to go on patrol at Bangor. The dolphins can find an intruder and release a beacon. Sea lions can attach a cuff to a swimmer's leg.