Rangiroa, which means "Far Sky" in Tuamotuan, is the largest atoll in the Tuamotus, and one of the largest in the world (larger than Kwajalein in the Marshall Islands). It is located in the Palliser group. The lagoon is approximately 65 km (41 miles) across. Its area is 1018 km².

The atoll consists of about 250 islands, islets and sandbars. There are approximately 100 narrow passages, called hoa, in the reef.

The chief town is Avatoru, located in the northwestern part of the atoll.