Coral Triangle

The Coral Triangle is defined by the boundaries of six nations: Indonesia, Malaysia, the Philippines, Papua New Guinea, Solomon Islands, and Timor-Leste.¹ Its shape approximates a triangle with vertices at the Philippines, the Solomon Islands, and Timor-Leste, encompassing the Sulu-Sulawesi Sea, the Banda Sea, and parts of the Bismarck Sea. The region covers roughly 5.7 million square kilometers of ocean, including some of the most remote and pristine reef systems on Earth.³ The area is a global crossroads of ocean currents, which helps distribute larvae and nutrients across the Indo-Pacific, sustaining high biodiversity far beyond its borders.

The Coral Triangle harbors the highest marine biodiversity on the planet, with over 600 species of reef-building corals—more than 75% of the global total—and more than 2,000 species of reef fish.⁴ It is also home to six of the world's seven marine turtle species, the whale shark, the manta ray, and the dugong. The region's seagrass beds and mangrove forests are among the most diverse in the world, providing critical nursery habitats. The extreme species richness is attributed to a combination of geological history, stable temperatures, and complex ocean currents that have created a center of speciation and endemism.⁴

The Coral Triangle faces severe threats from climate change, including coral bleaching and ocean acidification, as well as overfishing, destructive fishing practices, and pollution from coastal development. In response, the six nations formed the Coral Triangle Initiative (CTI) in 2007, a multilateral partnership to promote sustainable fisheries and marine protected areas.² Local and international organizations, including WWF and The Nature Conservancy, have established multiple marine protected areas, such as those in the Raja Ampat archipelago, which is part of the Birds Head Seascape. Despite these efforts, only about 3% of the Coral Triangle's waters are fully protected, and the region remains a hotspot for illegal, unreported, and unregulated fishing.¹

The term "Coral Triangle" was first popularized by WWF in the early 2000s to highlight the region's extraordinary biodiversity and the urgent need for conservation.¹ Among its most remarkable features is the Birds Head Seascape in West Papua, Indonesia, which alone contains more than 600 species of coral and 1,600 species of reef fish—among the highest counts per unit area.⁴ The Coral Triangle also serves as a global source of coral and fish larvae, which drift on ocean currents to replenish reefs across the Pacific, including the Great Barrier Reef. Additionally, the region has the highest diversity of mangrove species (over 40) and seagrass species (over 20) in the world, supporting complex food webs that sustain local communities. The Coral Triangle Initiative is unique as a government-led, region-wide effort, but funding and enforcement remain challenges.

Coral Triangle Initiative

A multilateral partnership formed in 2007 by the six Coral Triangle countries to address marine conservation and sustainable fisheries.

marine protected area

A designated region where human activities are restricted to conserve marine ecosystems.

biodiversity hotspot

A biogeographic region with high levels of species richness and endemism that is under threat.

coral reef

A diverse underwater ecosystem built by colonies of coral polyps held together by calcium carbonate.

seascape

A large-scale marine area with distinct ecological and geographical features, often managed as a conservation unit.