Marae Moana extends over 1.976 million square kilometres of ocean. This is the entire Cook Islands Exclusive Economic Zone which lies from 6 degrees south to 25 degrees south and 155 degrees west to 169 degrees west. The park is comprised of fifteen tropical islands with fringing coral reefs. These islands include seven atolls, four upraised coral reef islands (“makatea”), two sand cays, one almost atoll and one volcanic island. The open ocean dominates the park, with the islands making up only 237 square kilometres or 0.02% of the total area.
| Name of Island | Type of Island | Land Area (km2) | Human Population (2011) |
| Rarotonga | Volcanic | 67.1 | 13,095 |
| Aitutaki | Almost-atoll | 18.3 | 2,038 |
| Mangaia | Upraised limestone | 51.8 | 572 |
| Atiu | Upraised limestone | 26.9 | 480 |
| Mauke | Upraised limestone | 18.4 | 307 |
| Mitiaro | Upraised limestone | 22.3 | 189 |
| Palmerston | Atoll | 2.1 | 60 |
| Manuae | Atoll | 6.2 | 0 |
| Takutea | Sand Cay | 1.0 | 0 |
| Pukapuka | Atoll | 1.3 | 451 |
| Nassau | Sand Cay | 1.3 | 73 |
| Manihiki | Atoll | 5.4 | 239 |
| Rakahanga | Atoll | 4.1 | 77 |
| Penrhyn | Atoll | 9.8 | 213 |
| Suwarrow | Atoll | 0.4 | 0 |
Table 1 Islands within Marae Moana, their land area and human populationMarae Moana comprises several tropical ecosystems typical of tropical island environments. Coral reefs encircle all fifteen islands and these are separated by the pelagic ecosystem. Although there is no biological data, bathymetric data indicates there are possibly seamount ecosystems within the park. A variety of tropical forest ecosystems exist on the islands. These include littoral forests, the Rarotonga montane rainforest, Rarotonga cloud forest and makatea forest on the upraised limestone islands. Wetland ecosystems include streams, swamps and lakes. Unlike most tropical island environments, there are no mangrove or seagrass ecosystems in the Cook Islands, although there is archaeological evidence that the mangrove Rhizophora sp. previously existed in Mangaia. There are 136 identified coral species and some 650 species of fish in coral reefs of Marae Moana. Twenty two cetacean species have been observed in the open ocean.
| Species | Common Name |
| Megaptera novaeangliae | Humpback whale |
| Balaenoptera borealis | Sei whale |
| Balaenoptera musculus | Blue whale |
| Balaenoptera bonaerensis orBalaenoptera acutorostrata sp | Antarctic minke whale or Dwarf common minke whale |
| Physeter macrocephalus | Sperm whale |
| Orcinus orca | Killer whale |
| Globicephala macrorhynchus | Short-finned pilot whale |
| Ziphius cavirostris | Cuvier’s beaked whale |
| Mesoplodon densirostris | Blainville’s beaked whale |
| Peponocephala electra | Melon-headed whale |
| Balaenoptera edeni | Bryde’s Whale |
| Pseudorca crassidens | False Killer Whale |
| Delphinus delphis/frontalis | Common dolphin |
| Lagenorhynchus australis | Peale’s dolphin |
| Stenella longirostris | Spinner dolphin |
| Stenella attenuate | Striped/Spotted dolphin |
| Lagenodelphis hosei | Fraser’s dolphin |
| Grampus griseus | Risso’s dolphin |
| Steno bredanensis | Rough Toothed dolphin |
| Tursiops truncates | Bottle-nosed dolphin |
Table 2 Cetaceans found within Marae Moana (Source: Cook Islands Whale Research and Cook Islands Natural Heritage Project)
Three globally threatened marine turtle species have been identified in Marae Moana – the Green Turtle (Chelonia mydas), the Hawksbill Turtle (Eretmochelys imbricata) and the Loggerhead Turtle (Caretta caretta). The Green and Loggerhead Turtles are endangered and the Hawksbill critically endangered.
Tuna species typically identified in Marae Moana include Skipjack (Katsuwonus pelamis), Albacore (Thunnus alalunga), Yellowfin (Thunnus albacares), Bigeye (Thunnus obesus). Mackeral Tuna (Euthynnus affinis) and the Frigate Tuna (Auxis thazard). Big Eye Tuna (Thunnus obsesus) is identified as a globally threatened species with vulnerable status.
There are six reef shark species and eleven pelagic shark species found in Marae Moana.
| Species | Common Name |
| Nebrius ferrugineus | Nurse Shark |
| Carcharhinus albimarginatus | Silvertip Shark |
| Carcharhinus amblyrhynchos | Grey Reef Shark |
| Carcharhinus melanopterus | Blacktip Reef Shark |
| Triaenodon obesus | Whitetip Reef Shark |
| Hexanchus griseus | Bluntnose Sixgill Shark |
| Rhincodon typus | Whale Shark |
| Carcharhinus falciformis | Silky Shark |
| Carcharhinus galapagensis | Galapagos Shark |
| Carcharhinus longimanus | Oceanic Whitetip Shark |
| Galeocerdo cuvier | Tiger Shark |
| Prionace glauca | Blue Shark |
| Sphyrna lewini | Scalloped Hammerhead Shark |
| Alopias pelagicus | Pelagic Thresher Shark |
| Isurus oxyrinchus | Shortfin Mako Shark |
| Isistius brasiliensis | Cookiecutter Shark |
| Echinorhinus cookie | Prickly Shark |
Table 3 Shark species found within Marae Moana
Globally Threatened Species
With the support of Birdlife International, the Critical Ecosystems Partnership Fund, and help from the Cook Islands Natural Heritage Database, an analysis of Cook Islands Key Biodiversity Areas and Important Bird Areas was performed in 2012. The southern group islands are the most studied and therefore have the most comprehensive and reliable information. Marae Moana is home to 61 globally threatened species as well as many endemic species that are threatened. There are 25 threatened coral species, 8 threatened fish species, 3 marine turtle species and 3 threatened whale species. There are also 8 threatened land bird species, 11 threatened plants, one tree snail, one skink and one threatened seabird. Threatened species in the Marine Park are listed in Table 4.
| Threatened Coral Species | |||
| Acropora anthocercis | Staghorn coral | Leptoseris incrustans | Encrusting coral |
| Acropora globiceps | Staghorn coral | Montipora angulata | Montipora coral |
| Acropora horrid | Staghorn coral | Montipora australiensis | Montipora coral |
| Acropora microclados | Staghorn coral | Montipora calcarea | Montipora coral |
| Acropora palmerae | Staghorn coral | Montipora caliculata | Montipora coral |
| Acropora paniculata | Staghorn coral | Montipora lobulata | Montipora coral |
| Acropora polystoma | Staghorn coral | Pavona bipartite | Pavona coral |
| Acropora retusa | Staghorn coral | Pavona cactus | Pavona coral |
| Acropora speciosa | Staghorn coral | Pavona decussata | Cactus coral |
| Acropora striata | Staghorn coral | Pocillopora elegans | Pocillopora coral |
| Acropora vaughani | Staghorn coral | Turbinaria mesenterina | Pagoda coral |
| Alveopora allingi | Alveopora coral | Turbinaria reniformis | Yellow scroll coral |
| Alveopora verrilliana | Alveopora coral | ||
| Threatened Fish, Turtle & Whale Species | |||
| Alopias pelagicus | Pelagic Thresher Shark | Cheilinus undulates | Humphead Wrasse |
| Carcharhinus longimanus | Oceanic Whitetip Shark | Thunnus obesus | Big-eye Tuna |
| Taeniura meyeni | Giant reef ray | Eretmochelys imbricate | Hawksbill Turtle |
| Isurus oxyrinchus | Shortfin Mako | Chelonia mydas | Green Turtle |
| Rhincodon typus | Whale shark | Caretta caretta | Loggerhead Turtle |
| Epinephelus lanceolatus | Giant Grouper | Balaenoptera musculus | Blue Whale |
| Plectropomus laevis | Black Saddled Coral Grouper | Balaenoptera borealis | Sei Whale |
| Physeter macrocephalus | Sperm Whale | ||
| Threatened Bird Species | |||
| Pomarea dimidiate | Rarotonga Flycatcher | Todiramphus ruficollaris | Mangaia Kingfisher |
| Vini kuhlii | Rimatara Lorikeet | Vini peruviana | Blue Lorikeet |
| Collocalia sawtelli | Atiu Swiftlet | Aplonis cinerascens | Rarotonga Starling |
| Ptilinopus rarotongensis | Cook Islands Fruit Dove | Numenius tahitiensis | Bristle-thighed Curlew |
| Pterodroma leucoptera | Gould’s Petrel | ||
| Other fauna | |||
| Partula hyaline | Polynesian Tree Snail | Emoia adspersa | Micronesian Skink |
| Threatened Plant Species | |||
| Acrophorus raiatensis | Rarotonga Acrophorus | Cyrtandra rarotongensis | Rarotonga Cyrtandra |
| Asplenium schizotrichum | Polynesian Asplenium | Garnotia cheesemanii | Rarotonga Garnotia grass |
| Coprosma laevigata | Rarotonga Coprosma | Haloragis stokesii | Rarotonga Haloragis |
| Cyrtandra lilianae | Te Manga Cyrtandra | Psychotria whistleri | Rarotonga Psychotria |
| Radiogrammitis cheesemanii | Cloud grass fern | Sclerotheca viridifolia | Rarotonga Sclerotheca |
| Nesoluma polynesicum | Polynesian Nesoluma |
Table 4: Threatened Species in Marae Moana
Seabird Populations
The uninhabited islands of Takutea and Suwarrow are home to globally significant numbers of seabirds within Marae Moana. Suwarrow supports over 100,000 seabirds and nine resident species. The atoll supports globally significant proportions of the world’s Sooty Tern (Sterna fuscata), Lesser Frigatebird (Fregata ariel), and Red-Tailed Tropic Bird (Phaethon rubricauda) On Takutea, there is the Red-Tailed Tropic Bird, Brown Booby (Sula leucogaster), Masked Booby (Sula dactylatra), Red-Footed Booby (Sula sula), Great Frigatebird (Fregata minor), Brown Noddy (Anous stolidus), Black Noddy (Anous minutus) and White Tern (Gygis alba). Takutea also has globally significant populations of Red-tailed Tropic bird.
Key Biodiversity Areas and Important Bird Areas
Key Biodiversity Areas (KBAs) and Important Bird Areas (IBAs) are places that contain significant populations of globally threatened species. There are sixteen Key Biodiversity Areas within Marae Moana, seven of these are also Important Bird Areas.
Protected Areas
Marae Moana encompasses forty-one protected areas. These protected areas include twenty-six marine areas, seven marine-terrestrial areas, five terrestrial areas, two freshwater lakes and one saltwater marsh. The Cook Islands Whale Sanctuary encompasses the entire area of Marae Moana and still requires legal designation. Marae Moana is also a Shark Sanctuary, established through the Marine Resources (Shark Conservation) Regulations 2012. It is intended to assist communities with either the formal establishment or improved management of protected areas throughout Marae Moana.