Kiritimati, or Christmas Island, was encountered by James Cook during his third exploratory voyage in the Pacific. Following earlier expeditions that mapped various parts of the Pacific Ocean, Cook set sail in July 1776 aboard HMS Resolution, seeking to locate and survey the significant islands of the ocean. On December 24, 1777, while sailing through the equatorial region, Cook and his crew spotted the island, which was lush with vegetation and surrounded by a shimmering lagoon. Cook named the island in homage to the date of its discovery, aligning its title with Christmas traditions. The island's unique geographic structure characterized it as one of the largest coral atolls globally, stretching over 388 square kilometers.

The discovery was part of a broader effort by European explorers to expand their knowledge of the Pacific Islands, which were largely unknown to the Western world. Cook meticulously recorded his findings, marking the island’s latitude and longitude for future explorers and navigators. The significance of the charting of Kiritimati was immense, as it highlighted the potential for European maritime routes, and the natural resources available in the Pacific region. Its identification on maps led to increased interest from European powers regarding trade, colonization, and the expansion of their empires in the Pacific. Kiritimati remained uninhabited at the time, presenting an opportunity for various colonial powers to stake a claim in the region.