A U.S. Navy MH-60S Nighthawk helicopter from Helicopter Sea Combat Squadron (HSC) 4 flies over Marine Corps Base Hawaii -Kaneohe Bay, July 16, 2012, during Rim of the Pacific Exercise 2012 fast rope training with explosive ordnance disposal teams from United States, Australia, and Canada. Twenty-two nations, more than 40 ships and submarines, more than 200 aircraft and 25,000 personnel are participating in RIMPAC exercise from Jun. 29 to Aug. 3, in and around the Hawaiian Islands. The world's largest international maritime exercise, RIMPAC provides a unique training opportunity that helps participants foster and sustain the cooperative relationships that are critical to ensuring the safety of sea lanes and security on the worlds oceans. RIMPAC 2012 is the 23rd exercise in the series that began in 1971.