The Southern Group — Atiu (27 km²), Aitutaki (19 km²), Mangaia (52 km²), Manuae (6.2 km²), Mauke (20.3 km²), Mitiaro (22.8 km²), Palmerston (2 km²), Rarotonga (67 km²), and Takutea (1.2 km²) — has the Cooks Islands largest islands. They consist of a mix of high, rugged volcanic islands, raised coral islands and atolls. All members of the southern Group are inhabited except Manuae and Takutea.
Located around 1,000 km to the north of the southern islands are the Northern Group — Manihiki (5.4 km²), Nassau (1.2 km²), Penrhyn (10 km²), Pukapuka (4.3 km²), Rakahanga (4.1 km²), and Suwarrow (1.7 km²) — which, with the exception of the low coral island of Nassau, are all small to medium sized atoll formations. In comparison to the Southern Cook Islands they are isolated and much less developed.
1 Aitutaki
Aitutaki, located 247 km north from Rarotonga and 87 km northwest from Manuae, is a large triangular-shaped atoll of the Southern Group of islands, and is the second most populated island within the Cook Islands.
Aitutaki consists of a reef and associated reef flats (up to 1 km wide) encircling an extensive and very shallow lagoon. At the north and west of the lagoon is the large island of Araura covering 17 km², which rises to 124 m at Mt. Maungapu. In addition to Araura there are 21 smaller motu, covering 2.4 km². All but two of the islets run along the eastern edge of the atoll as an extension of the hook-shaped peninsula that emerges from the northeast corner of Araura. Many of these islets retain much of their native vegetation.
Araura
Maina
southeastern motu2 Atiu
Atiu, the third largest of the CooK Islands, is located 212 km northeast from Rarotonga and 76 km northwest from Mauke. The island is a raised coral island of just under 27 km² in area, largely surrounded by low limestone cliffs between 3 m and 6 m in height. From the edge of this raised platform the interior rises slowly to a plateau area of low hilly terrain. Surrounding the island is a narrow fringing reef up to 100 m in width, enclosing an even narrower lagoon.
3 Mangaia
Mangaia is the second largest — at nearly 52 km² in area — and also the most southerly of the Cook Islands, lying 194 km southeast from Rarotonga. Surrounding Mangaia is an ancient raised coral reef, rising steeply from the shore, before dropping sharply to the interior of the island. These ancient reefs rise up to 60 m in a series of layers, separating the hilly interior from the coast.
Geologically, Mangaia contains the oldest exposed volcanic rocks on the Pacific plate, with some its rocks being dated with ages of over 19 million years.
4 Manihiki
Manihiki is an atoll of the Northern Cook Islands, being located 43 km southeast from Rakahanga. The atoll, which is around 4 km across, consists of some 40 reef islets surrounding a deep cental lagoon which has no entrance passages to the open ocean. The islets of Manihiki have a combined land of area of 5.4 km² — the largest being the long and narrow Ngake which forms the entire northeastern border (bottom side in the above image) to the atoll. Dotted within the lagoon are are a number of tiny islets and numerous coral heads.
5 Manuae
Located 87 km southeast from Aitutaki, Manuae is an uninhabited atoll of the Southern Cook Islands. The formation consists of two islands: Manuae on the west side of the lagoon and Te Au O Tu in the east, with a combined area of 6.2 km². They are both enclosed within a small lagoon that is completely encircled by a breaking reef crest. Its waters are very shallow and contain large areas of sandbank.
13 km to the west of Manuae, the submarine feature known as the Astronomers Bank rises to within 300 m of the ocean surface. This is part of the same seamount that forms Manuae.
6 Mauke
Located in the Southern Cook Islands, 76 km southeast from Atiu and 270 km northeast from Rarotonga, Mauke is a raised coral island of 20.3 km², measuring 6.4 km north to south and 4 km east to west. The island is composed of a central plateau area of volcanic rocks, covering 5.4 km², that rises to a height of 30 m. Surrounding the central plateau is a raised coral reef (or makatea) separating the interior from the limestone perimeter (14.9 km²). This barrier (averaging around 5 m in height) to water draining off the plateau results in areas of swampland forming between the inner ramparts of the makatea and the interior. From the coastal fringe the island drops in low cliffs to a narrow reef flat (averaging 150 m in width) that surrounds the entire island.
7 Nassau
Nassau is an island in the Cook Islands.
Located 90 km south of Pukapuka, the small island (1.3 mi²/0.5 km²) of Nassau is just 9 metres (28 feet) above sea level, with an oval sandy cay on a coral reef foundation and is surrounded by a narrow reef flat. It is covered with palms, and is the only island of the Northern Group without a lagoon. The surrounding reef is 90 to 130 metres wide on all but the north side where it's narrower. The village is located in the north-west. Inland there are rich taro swamps and fruit groves, and offshore there is good fishing. It has a population of 71, according to the 2006 census, and a new harbour to be built later in 2007
8 Palmerston
Palmerston is a medium sized, low-lying atoll formation of the Southern Cook Islands, located 500 km to the northwest of Rarotonga and 360 km west-northwest from Aitutaki. Although Palmerston is a member of the Southern group, it lies far to the west of the other members of the southern islands — physically it has more common with the islands to the north.
Around the reef are six groups of islets, with the largest islets being Palmerston, North Island, Lee To Us, Leicester, Primrose, Toms and Cooks. Many smaller islets and drying banks can be found along the reef or grouped next to the larger islands. Total land area is around 2 km².
North Island
Leicester Island, Birds Islands9 Penrhyn
Penrhyn (also known as Mangarongaro) is the northernmost component of the Cook Islands, being located 1,365 km northeast from Rarotonga in the south. Vostok, the southernmost member of the Line Islands, lies 610 km to the southeast. It's nearest neigbour is the small atoll of Rakahanga, located 350 km to the southwest.
It is the largest atoll structure to be found in the Cook Islands, with a 77 km long reef rim enclosing a deep lagoon of 233 km² in area. Its numerous motus have a combined land area of 10 km². The lagoon, which has many patch reefs, is connected to the open sea by two well-formed passes: the Takuua Passage on the northeast side and the Siki Rangi Passage on the northwest.
Located around 5 km off the eastern side of the Penrhyn, opposite the Takuua Passage, sits the small Flying Venus Reef.
southern end
southeast
Siki Rangi Pass
Takuua Pass
west
Flying Venus Reef10 Pukapuka
northwesterly of the Cook Islands. The small atoll consists of 3 main islands lying at each point of a narrow triangular-shaped reef and several smaller motu, with a total land area of 4.3 km². From Motu Ko — the smallest of the main islands — extends the 4.5 km long Te Alai Reef which connects the main reefs of the atoll with the small cay of Toka. The lagoon of Pukapuka measures around 8 km in length and between 3 and 5 km in width; it contains extensive coral growth and numerous deep basins where water depths of up to 60 m are found.
11 Rakahanga
Rakahanga is an almost rectangular-shaped atoll of the Northern Cook Islands, located 43 km north from Manihiki. The atoll consists of two main islands and numerous smaller islets filling the gaps between the two largest islands — in all covering an area of 4.1 km². On the east these are: Akaro, Motu Ngangle, Huananul, Motu Mahuta and Motu Okakara; while on the southwest side the islet of Te Kainga guards the widest passage in to the lagoon.
12 At 67 km², Rarotonga is the largest of the Cook Islands, being located in the southwestern regions of the Southern group near the centre of the Cook-Austral chain of seamounts. The oval-shaped island measures 11 km in length (east to west) and has a maximum width of 8 km (north to south). It is the main population centre and administrative centre of the Cook Islands.
The island has a steep and rugged, densely forested interior, with the only flat land occurring as a narrow coastal strip around the perimeter. Erosional forces have created a highly dissected interior of sharp ridges and deep valleys that make much of Rarotonga inaccessible. The highest point of the island rises to a height of 652 m at Mt. Te manga. The entire island is, in turn, ringed by a narrow fringing reef that encloses a shallow lagoon.
13 Southernmost of the Northern Group, Suwarrow is located 950 km northwest from Rarotonga and 305 km southeast from the small island of Nassau.
The atoll consists of a broad reef rim of up to 800 m in width that almost completely encloses a large and deep central lagoon. Scattered around the outer reef are located around 40 small motu — none more than 0.1 km² in size — the largest islets being located on the western and northern sides of the atoll. The islets of Suwarrow have a combined area of just 1.68 km², making it the second smallest member of the Cook Islands in terms of land area after Takutea. The lagoon has numerous patch reefs and a major opening on the north between Anchorage Island and the Gull Islands.
Suwarrow is the first and only national park to have been created in the Cook Islands — being dedicated in 1978. The atoll is one of the Cook Islands major seabird breeding sites and has a regionally important population of the terrestrial Coconut Crab
northeast
northwest.14 Takutea
Takutea, located 23 km northwest from Atiu, is a small coral island of 1.5 km² in area rising to 6 m above sea level. A shallow water reef system surrounds much of the island and extends for around 3 km offshore on the southeastern side; closer to shore, a fringing reef wraps around the entire island. The interior is thickly wooded with Coconut palm (Cocos nucifera) and significant stands of Pisonia grandis; areas of scrub-type vegetation are also present. Takutea is uninhabited and is maintained as a wildlife sanctuary.
The wildlife sanctuary on Takutea helps to conserve the largest Red-tailed Tropicbird (Phaethon rubricauda) population found in the Central Pacific region. Other seabirds breeding on the island in regionally significant numbers include Red-footed Booby (Sula sula), Masked Booby (Sula dactylatra), Brown Booby (Sula leucogaster), and the Great Frigatebird (Fregata minor).
15 Mitiaro
Mitiaro makes up part of an island grouping called Nga-Pu-Toru. or "The Three Roots". The other two islands in the grouping are Atiu and Mauke. It's the flattest and economically, the poorest of the three. Like the other two, it was once a volcano that sank to become a coral atoll. It was also thrust upwards 10,000 years ago, but unlike the others, it only rose about 20 feet (6 metres). Despite that, its coral ring still died forming the makatea - a razor sharp ring around the island.
