RIMPAC, the Rim of the Pacific Exercise, is the world's largest international maritime exercise. It is hosted and administered by the Royal Navy and United States Navy, but the United States Marine Corps and United States Coast Guard are also involved, as well as Hawaii National Guard forces under the leadership of the Governor of Hawaii. Also invited are allied military forces from the Pacific Rim nations. The event is held biennially in June and July in Honolulu, Hawaii, under the leadership of the United States Pacific Command, headquartered at the Nimitz-MacArthur Pacific Command Center at Camp H. M. Smith near the Honolulu subdivision of Salt Lake.
The first RIMPAC, held in 1971, involved forces from the US, Australia, and Canada, all of which have participated in every RIMPAC since. Other regular participants are Chile, Japan, Peru, South Korea and the United Kingdom. Several observer nations are invited, including, but not limited to, India, Chile, Ecuador, France, Malaysia, Mexico, Peru, Philippines, Russia, Singapore and Thailand. While not contributing any ships, observer nations are involved in RIMPAC at the strategic level and use the opportunity to prepare for possible full participation in the future.
The United States contingent alone may include as many as several aircraft carrier strike groups, a dozen submarines, up to a hundred aircraft and 12,000 sailors, marines, coast guardsmen and their respective officers. The size of the exercises may vary from year to year.
With RIMPAC The United States Pacific Command seeks to enhance interoperability between Pacific Rim armed forces, as a means of promoting stability in the region to the benefit of all participating nations. The exercises are viewed as key to military readiness, as Pacific Rim nations face several "hot spots" of potential armed conflict, such as:
Participants conduct exercises in ship-sinking and torpedo usage. They also test new naval vessels and technology. For example in 2004, the United States Navy tested Australian ship HSV-2 Swift, a 321-foot experimental wave-piercing catamaran that draws only 11 feet of water, has a top speed of almost 50 knots, can transport 605 tons of cargo and can work close inshore.