Mapping a changing ocean

11 September 2026

A celebration in Rarotonga in August marked the successful completion of a major ocean science voyage that will help the Cook Islands build a long-term understanding of how climate change is affecting its vast ocean territory.

Undertaken aboard research vessel Kaharoa II, the month-long expedition was a partnership between Climate Change Cook Islands and Earth Sciences New Zealand (ESNZ- formerly NIWA), and forms the first phase of the Cook Islands Ocean Monitoring Programme.

The programme aims to establish the first comprehensive baseline of ocean conditions across the Cook Islands Exclusive Economic Zone (EEZ), creating a foundation against which future environmental changes can be measured.

The voyage is part of the Enhancing Climate Information and Knowledge Services for Resilience in Five Island Countries of the Pacific Ocean (CIS-Pac5) programme, funded by the Green Climate Fund. The expedition collected observations from the surface to depths of more than 5,000 metres, including measurements of ocean temperature, currents, water chemistry, plankton, microplastics and seafloor characteristics.

Climate Change Cook Islands Director Wayne King said the project would provide the foundation for understanding how the country's ocean changes over time. “The idea of it is to capture what we call baseline. That's all the information from the surface of the ocean right to the very bottom, and that will allow us to then know what changes will occur to that ocean over time.” He added, “We are an ocean state. Very small country land-wise, very big country ocean-wise. So we need to understand if there is change in those oceans.”

The project also reflects a commitment to building Pacific capability and ensuring Pacific communities are directly involved in research taking place in their waters. Two Cook Islands researchers joined the voyage: Tangimetua "Tango" Paerau from Kōrero O Te 'Ōrau and Karen Silk from the National Environment Service, helping strengthen local knowledge and connections that will support future ocean monitoring activities.

The voyage concluded with a welcoming ceremony in Rarotonga attended by Cook Islands Prime Minister Hon. Mark Brown, government representatives, project partners, and community members. The event celebrated not only the successful completion of the expedition, but also the strong partnership between the Cook Islands and New Zealand and a shared commitment to understanding and protecting the Pacific Ocean.

Speaking at the event, ESNZ Chief Science Operations Officer Helen Neil highlighted the broader value of Pacific science partnerships.

“Today is an opportunity not only to celebrate a remarkable voyage, but also to reflect on the value of science partnerships and the role they play in supporting resilient Pacific communities.”

The information collected during the voyage will now be analysed and incorporated into long-term ocean monitoring and climate resilience initiatives. The data will strengthen understanding of how ocean temperatures, currents, chemistry and ecosystems are changing, supporting future decision-making and resilience planning in the Cook Islands and across the wider Pacific. As ESNZ oceanographer and voyage leader Denise Fernandez noted, establishing a robust baseline today will help scientists and Pacific decision-makers better understand and prepare for the changes that lie ahead.

“The more information we gather, the more information we can provide to those models, the more we can know about the future."

This collaboration lays the foundation for a long-term ocean monitoring programme that will help ensure the Cook Islands and the wider Pacific region are better equipped to respond to a changing ocean.