The Bunaken National Marine Park was formally established in 1991 and is among the first of Indonesia's growing system of marine parks. The park covers a total surface area of 89,065 hectares, 97% of which is overlain by sparkling clear, warm tropical water. The remaining 3% of the park is terrestrial, including the five islands of Bunaken, Manado Tua, Mantehage, Nain and Siladen. Although each of these islands has a special character, it is the aquatic ecosystem that attracts most naturalists.

The waters of Bunaken National Marine Park are extremely deep (1566 m in Manado Bay), clear (up to 35-40 m visibility), refreshing in temperature (27-29 C) and harbor some of the highest levels of biodiversity in the world. Pick any of group of interest - corals, fish, echinoderms or sponges - and the number of families, genera or species is bound to be astonishingly high. For example, 7 of the 8 species of giant clams that occur in the world, occur in Bunaken. The park has around 70 genera of corals; compare this to a mere 10 in Hawaii. Although the exact number of fish species is unknown, it may be slightly higher than in the Philippines, where 2,500 species, or nearly 70% of all fish species known to the Indo-western Pacific, are found.