A NASA satellite has captured a striking turquoise and green halo surrounding New Zealand’s Chatham Islands, revealing a large summer phytoplankton bloom shaped by ocean currents and an underwater plateau.
The image, recorded on January 10, 2026, by the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the NOAA-20 satellite, shows swirling bands of phytoplankton around the remote island group located about 800 kilometres east of New Zealand’s South Island.
Scientists said the bloom was driven by the Chatham Rise, a vast underwater plateau measuring about 800 kilometres long and 300 kilometres wide. The submerged feature helps maintain the boundary between cold, nutrient-rich Antarctic waters and warmer subtropical waters, creating favourable conditions for phytoplankton growth during the Southern Hemisphere summer.
Once formed, ocean currents and eddies stretched the bloom into loops, filaments and spirals, creating the distinctive turquoise halo visible from space.
Phytoplankton are microscopic organisms that use sunlight to produce energy through photosynthesis. They form the foundation of marine food webs, supporting zooplankton, fish, seabirds, seals and whales.
Researchers noted that while satellite observations can detect the location and movement of phytoplankton blooms by measuring ocean colour and chlorophyll concentrations, they cannot identify the species involved. Direct sampling of seawater is required to confirm the organisms responsible.
The waters around the Chatham Islands support commercially and ecologically important species such as pāua (abalone), rock lobster and blue cod, as well as several species of seals, whales and dolphins.
Scientists said similar phytoplankton blooms were observed in the region in 2008, 2009 and 2010, suggesting the phenomenon is a recurring seasonal event rather than an isolated occurrence.
The observation has been published by NASA Earth Observatory.