The fringing reef creates a massive protected natural harbor which has a total area of more than 2,000 square kilometers. The lagoon is famous to divers for the extensive Japanese WWII wrecks which were sunk by the Allied forces in 1944. Up until then it had been used as the main base for the Japanese Naval forces in the Pacific.

There are over 30 naval ships and 250 aircraft in the lagoon, many just 15 meters below the surface and within recreational diving limits. Others are deeper still and are popular for technical diving on trimix or rebreathers. As the waters within the lagoon are calm and protected from ocean currents, visibility is nearly unlimited. Many of the ships still have cargo and supplies including munitions, mines, and medical items; along with some human remains which divers can encounter from time to time. The extensive amount of sunken military vessels and aircraft have come to be known as the "Ghost Fleet of Truk Lagoon".

Above water the fringing protective coral reef harbors several large island groups, known as the Faichuk and Nomoneas Islands. These islands rise up from the perfect blue waters of the lagoon to altitude of 443 and 370 meters respectively. This is where the majority of the state’s population of more than 10,000 live.

The island is reached by flights through the Marshall Islands three times a week and from Guam five times a week. As the islands are located just 7 degrees north of the equator, the climate is consistent all year, with lighter amounts of rain from January to March, and an average of 31 cm (13 inches) of rainfall for the rest year.