New Tūhua/ Mayor Island Volcano resource now available

Monday, 3 November 2025

Off the coast of western Bay of Plenty sits Tūhua/ Mayor Island. An island famous for big-game fishing & diving, and a haven for wildlife as a pest-free sanctuary. But did you know it is also a dormant volcano?

Being dormant, the volcano is not currently active or restless but could erupt again. The island we see is actually the volcano summit, rising about 600 metres from the seafloor and stretching 6km in diameter underwater.

Tūhua is one of New Zealand’s closest offshore volcanoes and has a fascinating story to tell. To help tell it, Earth Sciences New Zealand have created a brand-new fact sheet with the latest scientific research under their Beneath the Waves programme. 

Find the Tūhua/ Mayor Island factsheet on the Beneath The Waves website. 

Understanding our volcanoes helps us stay safe and connected to the land. While an eruption is unlikely within our lifetimes, GeoNet constantly monitors the island and will provide updates on any change in activity.

While you're here, find some Tūhua quick facts below:

• Geologically, Tūhua is a collection of overlapping volcanic shields and pumice cones, and several collapse calderas
• Tūhua has erupted at least 31 times in the past 54,000 years, with large eruptions every 7,000–8,000 years
• Its lava cools quickly to form black volcanic glass (obsidian) which is where the island gets its Māori name
• The magma is unusually runny for its type, meaning it can erupt explosively or as lava flows – a rare trait compared to other NZ volcanoes
• Tūhua is dormant, meaning it’s not showing signs of activity, but it could erupt again

Illustration credit: Gavin Mouldey