Penrhyn is an atoll in the northern group of the Cook Islands in the south Pacific Ocean. The northernmost island in the group, it is located at 1,365 km (848 mi) north-north-east of the capital island of Rarotonga, 9 degrees south of the equator. Its nearest neighbours are Rakahanga and Manihiki, approximately 350 kilometres (220 mi) to the southwest. Once one of the most heavily populated atolls, it was almost completely depopulated by Peruvian slavers in 1864.

The Cook Islands is an island country in Polynesia, part of Oceania in the South Pacific Ocean. It consists of 15 islands whose total land area is approximately 236.7 square kilometres (91 sq mi). The Cook Islands' Exclusive Economic Zone (EEZ) covers 1,960,027 square kilometres (756,771 sq mi) of ocean. Avarua is its capital.