The park waters are clear and warm with a diversity of coral and fish populations. View the list of Corals (many are illustrated).  Over 200 coral species occur in the territory, representing about one third of all coral species found throughout the Indo-Pacific region. Dominant genera are Montipora and Porites, followed by Pavona, Pocillopora, Psammocora and Acropora.

Most park waters have fringing coral reefs. The reefs typically have a reef flat or shallow backreef moat, a reef crest (often emergent at low tide), surge zone (with spur and groove formation on the south-west windward side) and a sharp reef front dropping 5-10 m to a reef terrace and gradually descending to deep water.