Wild kelp forests and predator free islands off the Coromandel coast
Updated Nov 21, 2025 • 9 sources
Top species linked to approved dive spots in Mercury Islands (Coromandel Peninsula).
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Last updated: November 21, 2025 • 9 sources
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Overview
The Mercury Islands, or Nga motu o Ahuahu, are a cluster of predator free islands sitting off New Zealands Coromandel Peninsula. Based out of Whitianga in Mercury Bay, divers and snorkellers cross 15 km of open water to reach sheer walls, kelp forests and fish filled pinnacles that feel far wilder than the mainland coast. Great Mercury Island (Ahuahu) welcomes low impact day visitors, while the six smaller islands are DOC managed nature reserves with strict no landing rules and globally significant seabird and reptile communities. Underwater, the Mercs mix easy sheltered bays with advanced, current swept sites that attract schooling kingfish, trevally, rays and the occasional orca. Exotic Caulerpa restrictions and a no take zone around Ahuahu make this a true look dont touch destination for conservation minded divers, freedivers and snorkellers.
Pest-free offshore islands keep bird and lizard colonies intact and the surrounding reefs lively.
From Whitianga, day boats reach bays, walls, and pinnacles in about an hour, delivering offshore viz and schooling pelagics.
Great Mercury’s Controlled Area bans take and requires strict gear cleaning, keeping it a rich no-take zone.
Kelp, sponges, and boulder walls give temperate macro habitat and playful reef fish instead of tropical coral.
7 linked spots
Best time to go
January - April
Warmest water near 20°C, long daylight, frequent light winds and settled high pressure. Accommodation and charters are busiest from late December to early February.
Main caution: Coolest water and air, more frequent swell and strong wind events, but also occasional crystal clear, calm days under winter high pressure systems.
