Diving Mayor Island

Mayor Island is a dormant shield volcano off the Bay of Plenty coast of New Zealand's North Island. It is 35 km (22 mi) north of Tauranga and has an area of 13 km² (5 sq mi). The island has a mostly precipitous coastline, and maximum height of 355 m (1,165 ft) above sea level.

The island is thought to have risen from the sea about 7000 years ago, and the most recent lava flows have been dated at between 500 and 1,000 years old.

Weather reports for coastal weather region Plenty are broadcast on VHF. The nearest weather stations are Slipper Island and White Island.

Water temperature may be as low as 14°C

The waters within 800 m of the north shoreline are a marine reserve.

Regular recreational diving equipment is adequate for most dives in this region.

Understand: — An open bay under a high cliff, with sand bottom and good anchorage. Bands of black obsidian can be seen glittering in the strata of the cliff face, and shards are scattered on the bottom.

Position: — S37.28588° E176.27328° About halfway along the east side of the island. The crater is just over the cliffs.

Depth: — Fairly shallow.

Topography: — Shoreline reef starts about 3.5m deep. Medium to low profile rocky reef mostly of boulders with occasional outcrops.

Marine life and features: — Mostly quite heavy growth of wide range of turf seaweeds. Not much fish life and not much mobile invertebrate diversity.

Conditions: — Good anchorage on sand bottom at about 8m depth.

Understand: — The next bay north of Crater Bay, characterised by a small inshore islet with a natural arch through it, and an underwater ridge running seaward from the islet. Reasonable anchorage on rocky reef, but fairly deep, at about 20m. Some risk of anchor fouling due to bottom structure.

Position: — S37.27681° E176.27820°

Depth: — depth increases rapidly to over 20m within a short distance from the shore.

Topography: — Short arch tunnel through small volcanic rock islet right up near shoreline cliffs. Archway about 7m deep. similar width and height above water. Gulley inshore about 9m with narrow sand bottom. Gully offshore considerably deeper.

Marine life and features:— Fairly barren rock surface in archway. Also fairly barren in gulley but some kelp and small amounts of other seaweeds. Much more lush reef cover further out on the seaward face.

Conditions: — Very well protected from westerly winds and swell, and moderately protected from northerly and southerly winds and swell, but very exposed to anything from the east.

Understand: — Large offshore reef to the south east of Mayor Island. It is not in a marine reserve, and there are usually a large number of lobster pots with their associated floats over the shallower areas. This is a mixed blessing, as they help to identify the reef, help to keep station, but are a serious risk of fouling the propellers.

Position: — S37.30528° E176.28799°

Depth: — 6 to 60m

Topography: — Large reef with depths from 6m down to over 60m on the outside edges. Large shallow area above 10m, with deep and shallow gullies

Marine life and features: — Very heavy and healthy kelp cover. Large numbers of fish on a good day. Moderate variety of invertebrates present but you have to go looking for them in the gullies.

Conditions: — This is an open water reef, exposed to the wind from all directions, but moderately protected from swell from the west and north west.

Understand: — A small point and south east facing bay just to the east of South East Bay anchorage.

Position: — S37.30475° E176.26796°

Depth: — at least 12m deep.

Topography: — Rocky reef, probably volcanic sediments. Moderate profile ridges and gullies. Rock fairly porous and weathered with odd holes and crevices

Marine life and features: — Heavy kelp cover except on walls and in shallows.

Conditions: — Exposed to wind and waves from the south and east, protected from north easterly to south westerly wind and swell.

Understand: — Offshore reef, but not very far offshore, so it is partly protected by the island from wind, and waves.

Position: — S37.25845° E176.26906°

Depth: — 3 to 40m.

Topography: — Large flattish topped rocky reef with some deep gullies and steep sections. Some parts moderately sloped with fairly high profile.

Marine life and features: — Marine reserve. Heavy kelp forest in healthy condition. Moderate fish diversity. Large shoals of koheru, blue mao mao, trevally and kingfish may be seen above the top of reef, demoiselles a little deeper.

Conditions: — Very well sheltered from wind and swell from the south west to south east, but quite exposed to the north. Anchorage on rocky reef with some risk of fouling. Check the anchor at the start of a dive.

Understand: — A small islet just off the north shore of Mayor Island.

Position: — S37.26558° E176.27007°

Depth: — up to about 18m.

Topography: — Fairly steep sides to the islet, with relatively flat reef between the rock and the main island.

Marine life and features: — Marine reserve. Heavy kelp in good condition. Moderate variety of fish but not much in mobile invertebrates.

Conditions: — Anchorage in the channel is fairly secure in depths of around 18m, but on quite rugged reef, so there is a risk of fouling the anchor. Check during the dive. Sheltered from wind and swell from the south but exposed to the north.

Hazards: — Fairly strong currents may flow between the islet and the main island, which can make it difficult to swim back to a moored boat. These currents can develop quite quickly and may be tidal.

Equipment: — A drift line is worth considering when diving from a boat anchored in the channel.

Understand: —

Position: — S37.26878° E176.24698°

Depth: — 8 to 25m

Topography: — High profile boulders and bedrock at base of cliff with lots of gaps, holes, overhangs, gullies and pinnacles.

Marine life and features: — Marine reserve. Kelp below about 6m and dense growths of other seaweeds above. Not much in mobile invertebrates but fair number of Kina.

Conditions: — Surge can be very strong in the inshore gullies and over the tops of large boulders. Exposed to wind and swell from the north, but well protected from weather from the south.

Understand: — A small bay under the cliffs at the western end of the marine reserve.

Position: — S37.27266° E176.24120°

Depth: — 10 to 25m

Topography: — The reef to the south east of the bay starts at about 9m, with sand bottom sloping gradually down to the north to at least 12m. Sand bottom from 12m to 9.5m then boulder field of large and small boulders and some bedrock. Low ridges perpendicular to shoreline.

Marine life and features: — Marine reserve. Moderate density kelp on top of most rocks but also other weeds and some areas relatively barren. Fair numbers of fish may be present over the reef.

Conditions: — Exposed to wind and waves from the north, but very well protected from anything from the south.

Hazards: — Surge may be very strong in the shallows