尼库马罗罗环礁是太平洋岛国基里巴斯的环礁，属于凤凰群岛的一部分，长7.5公里、宽2.5公里，土地面积4.1平方公里，潟湖面积8平方公里，该岛自1965年无人居住。

Nikumaroro, or Gardner Island, is part of the Phoenix Islands, Kiribati, in the western Pacific Ocean. It is a remote, elongated, triangular coral atoll with profuse vegetation and a large central marine lagoon. Nikumaroro is approximately 7.5 kilometres (4.7 mi) long by 2.5 kilometres (1.6 mi) wide. There are two narrow entrances through the rim, both of which are blocked by a wide reef which is dry at low tide. The ocean beyond the reef is very deep and the only anchorage is at the island's west end, across the reef from the ruins of a mid-twentieth-century British colonial village, but this is safe only with the southeast trade winds. Landing has always been difficult and is most often done south of the anchorage. Although occupied at various times during the past, the island is uninhabited today.