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Dive Sites

Te Whanaganui-A-Hei (Cathedral Cove) Marine Reserve.

Te Whanganui-A-Hei Marine Reserve was established in 1992. There are rich and varied habitats within its boundaries and the Reserve is helping to restore, increase and maintain the diversity in this marine environment. The vision is of a well managed reserve, bountiful in marine life, respected and enjoyed by the public for generations to come.

The marine reserve covers 9 square kilometres on the Pacific East coast of the Coromandel and is administered by the Department of Conservation in partnership with the Te Whanganui-A-Hei Marine Reserve Committee.

Coastal and island boundaries are indicated by yellow poles. Floating boundary markers are in place off the north eastern corner of Mahurangi Island and midway along the seaward boundary (see map). Flashing yellow lights operate from dusk to dawn; these are visible for one nautical mile.

The Aldermen Islands

Crystal clear water so blue it’s almost purple, abundant sealife including marlin & yellowfin, and water a warm 23.8 degrees. At the time of writing this is the Aldermen Islands, many would say the jewel in the crown of Coromandel diving.

Located off the eastern coast of the Coromandel Peninsula(@ 12k from Tairua) the islands cover an area of about 133ha. There are approximately 40 islands forming three main areas of the Sugar Loaf Rocks, Hongiora (Flat) Island and the main group (Ruamahanui, Middle, Ruamahuaiti, and Nga Horo Islands).

The location offers a huge array of diving on blue-water pinnacles, walls and shallow reefs, and an even huger array of marine life inhabiting those areas. Comparisons with the Poor Knights are often made.

A diverse area such as the Aldermens also offers diving for divers of all experience levels and in variable weather conditions.

Not only is the diving a treasure but the islands are a Wildlife Sanctuary (1933), with only authorised scientific personnel allowed to land there. The group is home to a significant colony of tuatara, and numerous bird colonies.

The inhospitable (to humans) nature of the terrain has provided protection to species that have otherwise become extinct on the mainland.

The island group is so named by Captain Cook and his crew of the Endeavour in 1769. “At 7 a.m a cluster of small island and rocks bore distant one League…The cluster of Islands and rocks just mention’d we named the Court of Aldermen… some of them are as small of compass as the Moniment in London and spire up to a much greater height and some of them are inhabited”, writes Cook.


Danger Rocks

Between Ohinau Island & Whale rock. Reef dropping off to 30m, large valleys with sandy bottoms, large cracks along valley walls, lots of swim throughs, pinnacles, flat top rocks covered in sea weed and kelp.


Orua Bay

South Mercury coast, between Hahei and Hot Water Beach. Small bay with rock wall on one side and boulders on the bottom and other side mostly covered with seaweed.

There are a few nice big caverns to one side of the bay that are worth a look, surge permitting, depth drops off to 25m at the entrance to the bay.


The Bookcase

Western side of Great Mercury Island, bookcase shaped rock. Really nice straight wall dive onto sandy bottom. Most can circumnavigate the rock in a single dive. Beware of surge on the corner closest to Great Merc. Nice long cracks and crevices all the way round, then interesting rock formations around the inside corner.


Joshuas Rock

Around the Southeastern corner of Great Mercury Island. Pinnacles coming out of 40m+ give an awesome site with ledges at about 14m and 30m allows for a perfect multilevel dive following the ledges up and around spiraling towards a safe ledge for a safety stop.
Lots to explore with swim throughs and big crevices .


Ohinau Island

Huge variety of diving here from shallow reefs to deep wall drop offs, mostly broken rock and boulder country.
Some large cracks and crevices and some very nice swim throughs. The south western side has lots of seaweed whereas the north eastern face is mostly bare rock with a few weed edges.


Centre Island

Center of Mercury Bay out from Buffalo Beach, Center Island is situated on the edge of the Te-Whanganui-a-hei marine reserve. Rocky reef dropping off to sand, Center Island has a vast range of terrain, from walls to rocky out crops, including large cracks and crevices. There are areas of dense seaweed, but also large areas of bare rock.


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