Komodo: Sangeang Volcano – Bonto Dive Site – Komodo National Park

Site Overview

Sangeang Volcano Bonto is a dive site on the slopes of Sangeang Api, an active volcanic island northeast of Komodo National Park that creates an extraordinary underwater environment shaped by ongoing volcanic activity. Bonto features a dramatic wall formation on the island's western slope, where volcanic rock creates vertical terrain descending from 5 meters to 30 meters. The volcanic substrate supports a distinctly different marine ecosystem than the coral-dominated sites elsewhere in Komodo, with black volcanic rock covered in colorful soft corals, crinoids, and sponges that thrive in the mineral-rich water. Thermal vents at 18 to 25 meters release warm mineral-laden water that creates shimmering thermoclines and supports unusual chemosynthetic organisms found nowhere else in the park. The wall hosts pygmy seahorses on the gorgonian fans, ghost pipefish among the crinoids, and an extraordinary diversity of nudibranch species adapted to the volcanic environment. Whitetip reef sharks patrol the ledges, schools of barracuda and trevally gather in the current, and the shallower black sand patches at 5 to 12 meters harbor garden eels and shrimp gobies. The volcanic bommies at 12 to 20 meters are covered in vibrant orange and yellow soft corals that contrast dramatically with the dark volcanic rock. Sangeang is best dived from April through December when the seas are calm enough for the longer boat journey. Bonto showcases the extraordinary intersection of volcanic geology and marine biology that makes Sangeang one of the most unique dive destinations in Indonesia.