Chatham Islands Anniversary Day in New Zealand Date in the current year: December 1, 2025

The Chatham Islands, also known as the Chathams, are a remote archipelago in the Pacific Ocean. They are located about 800 km (500 mi) east of New Zealand’s South Island. Administered as part of New Zealand, the islands have a resident population of 620 as of June 2025. Most Chatham Islanders live on Chatham Island, the largest island in the group, and a few dozen live on Pitt Island.

The first settlers on the Chatham Islands were the Moriori, a Polynesian ethnic group who arrived from the New Zealand mainland around the 15th century. The Moriori and Māori share the same origin, but their language and culture diverged due to the Moriori’s isolated life on the Chathams. Today, they are recognized as New Zealand’s second indigenous people.

The Moriori lived in isolation until Europeans arrived in the late 18th century. The first Europeans to set foot on the archipelago were crew members of the HMS Chatham, which was part of the Vancouver Expedition. On November 29, 1791, they landed on the main island, and the ship’s commander, Lieutenant William Robert Broughton, claimed the islands for Great Britain.

After the islands were discovered, sealers and whalers began establishing their bases there. As a result, it is estimated that 10-20% of the Moriori population died from diseases introduced by Europeans. In the mid-19th century, the sealing and whaling industries ceased operations in the region, though fishing remained prevalent. The Chatham Islands officially became part of the New Zealand colony in 1842 after an attempt to sell the islands to Germany failed.

The first Māori settlers, led by Chief Pōmare Ngātata, arrived in November and December of 1835. Initially, the locals warmly received them because they adhered to the principle of non-violence. However, the Māori soon conquered the Moriori’s lands, murdering several hundred people and enslaving the rest. The Moriori remained enslaved until 1863 when the British colonial government released them. The Moriori genocide caused the indigenous population of the Chatham Islands to drop from 1,700 to around 150 people. By the end of the decade, most of the Māori had returned to Taranaki.

Today, most residents of the Chatham Islands are of European (Pākehā), Māori, or mixed European-Māori ancestry, while most New Zealanders of Moriori ancestry now live on the North and South Islands. The local economy depends largely on fishing, crayfishing, and farming, as well as adventure tourism to a lesser degree.

Although November 29 is the actual anniversary of the Chatham Islands, Chatham Islands Anniversary Day is celebrated on the Monday closest to November 30 in order to create a long weekend. This holiday falls on either the last Monday in November or the first Monday in December. It is a public holiday and nonworking day in the Chatham Islands but not in the rest of New Zealand.