Manado Tua (Old Manado) Island, together with the islands of Bunaken, Siladen, Mantehage and Nain form the Bunaken-Manado Tua Marine National Park. The Park lies just off shore from the city of Manado, capital of the province of North Sulawesi. Covering a total of 89,065 hectares, the Bunaken-Manado Tua park is among the most spectacular dive sites in the world. The islands are separated from the mainland by a submarine trench that reaches a depth of 1,200 meters, and keeps these waters relatively free from city garbage and silt. The reserve is protected by law from spearfishing and coral or fish-collecting, as well as from dynamite fishing.

The island has some 3,200 inhabitants forming a tight-knit community of farmers and fishermen from the Sangir region. This community has been actively restoring damaged reefs with the assistance of Seacology. Around the island are underwater plateaus sloping from 5-30 meters, fringed by vertical coral walls plunging 25-50 meters down, and large caves with hanging coral reefs: a truly amazing sea garden.