A 140-mile barrier reef encircles Chuuk (Truk Lagoon) and the eleven high islands within — a naturally protected harbor in the middle of the Pacific. Perfect, thought the Japanese military planners; in 1918 they established what would become a massive military base operation. Eventually, five airfields supporting close to 500 aircraft, plus patrol boats, torpedo boats, submarines, tugs, landing craft, gunboats and mine sweepers, contributed to the final defenses and service needed to maintain this big base. In 1944, Chuuk, known until recently by the Western mispronunciation, Truk, was again declared perfect — this time by the American and Allied forces who had identified Chuuk as ideal for staging their own move into Japan to defeat the enemy. Operation Hailstone was unleashed during two days in February, when wave after wave of torpedo bombers emptied their loads onto the unsuspecting target. The Japanese retaliation attempt was futile and their operations were permanently disabled. Twenty-five years later, diving came to Chuuk — not to see the plunging vertical walls that line the atoll and are worth the trek alone, but to begin exploring the Japanese ships and planes that litter the seafloor, whispering their violent ends to divers from the world over. Viewing them today, it's hard to believe that these canvases of psychedelic color — festooned with brilliant soft corals and anemones that attract many of the Lagoon's 700 species of fish and pelagic predators such as gray reef sharks — were once dramatic tools of war. Sign on with the live-aboard SS Thorfinn to experience the dive equivalent of a moveable feast — hitting thirty different wrecks in a week's time. The Thorfinn acts as a floating hotel from which smaller boats are dispersed to the wrecks with a maximum of six divers in each. Expert guides lead incredible tours inside huge, ghostly, impressive interiors that are still filled with cargoes of aircraft, trucks, tanks and tractors … and quantities of beer and rice wines that indicate that not all was sweat and tears in that war of long ago. The 500-foot Shinkoku Maru serves as a rest stop of sorts for the abundant fish life and sharks swimming in the current both off the bow and midship. Be sure to explore the midship, where you'll find the galley — easily identifiable by the plates and cooking utensils that are still visible. Watch for an operating table and blankets buried in the silt. The Hanakawa Maru is a rarely visited but ideal dive that wasn't determined safe for divers until 1990. The ship can be viewed at depths ranging from 50 to 110 feet and is one of the most colorful in the lagoon, bejeweled with hard and soft corals and multicolored crinoids.