The island is volcanic in origin and forms the southwest rim of the Laguna Caldera.

[2] The island consists of 24 barangays that lie along its shores, 17 belong to the town of Binangonan and 7 to Cardona.

The northernmost tip of the island is separated from the mainland by Diablo Pass, which is only about 240 meters (790 ft) at the narrowest.

This feature is best observed from neighboring Mount Sembrano in the Jalajala peninsula across the lake.

Also, a few Jehovah's Witnesses[7][8] live on the island, and they have three meeting places called Kingdom Halls.