加罗林岛（英语：Caroline Island）也被称作千禧岛（英语：Millennium Island）是太平洋上基里巴斯共和国莱恩群岛东南端的一个无人居住的环礁。岛上富有海鸟粪资源，是世界上最大的椰子蟹栖息地之一。

加罗林岛及其所在的莱恩群岛原位于国际日期变更线以东，但基里巴斯政府在1995年把日期线东移，使属于该国的莱恩群岛改用UTC+14时间，以消除与首都塔拉瓦在日期上相差一天的不便。这也使得加罗林岛在2000年1月1日成为最早看到新千年日出的地区之一。

Caroline Island or Caroline Atoll (also known as Millennium Island and Beccisa Island), is the easternmost of the uninhabited coral atolls which comprise the southern Line Islands in the central Pacific Ocean.

First sighted by Europeans in 1606, claimed by the United Kingdom in 1868, and part of the Republic of Kiribati since the island nation's independence in 1979, Caroline Island has remained relatively untouched and is considered one of the world's most pristine tropical islands, despite guano mining, copra harvesting, and human habitation in the 19th and 20th centuries. It is home to one of the world's largest populations of the coconut crab and is an important breeding site for seabirds, most notably the sooty tern.