Sangeang Volcano - Indonesia's best-kept diving secret

Indonesia offers many spectacular diving sites, but this one is still a secret. Sangeang volcano on the coast of Sumbawa is home to the best macro diving sites in the world. Volcanoes might have a bad reputation, but volcanic debris is quite fertile and creates life. Underwater, the debris transforms into a magical substance that hosts countless marine life and forms beautiful shapes. So, no wonder that some of the best macro diving in the world is often found around volcanic reefs. Visit Sangeang volcano with one of our unique private boat charters

Interesting Facts about Sangeang Volcano

Sangeang volcano has a long history of eruptions, with recorded eruptions dating back to the 16th century. Its most recent eruption was in 2014, which produced ash plumes that reached an altitude of 15,000 feet (4,600 meters). In addition, the volcano holds cultural significance for the local population, who believe that it is inhabited by a spirit that protects the island and its people. They perform regular ceremonies and offerings to appease the spirit and prevent eruptions.

Discover Sangeang in Sumbawa 

Volcanic Dive Sites

Biodiversity and volcanic activity merge to create macro heaven. Due to the mineral-rich substance, many rare and unique critters find their home in volcanic ash. If you like frogfish, pygmy seahorses, or mimic octopus, diving volcanic reefs is a must. There are more than 125 volcanoes in Indonesia, but not every one of them hosts a reef nearby. Sumbawa, in the West Nusa Tenggara region, is home to one of the hidden gems of Indonesian diving – Gunung Api Sangeang.

Black sand and macro diving delights around Sangeang

Situated about 10 kilometers offshore from Bima airport, Api Sangeang is an imposing, but scenic, volcano complex. There has not been an eruption since 2014, but its twin cones regularly send plumes of ash and smoke into the sky. Keep an eye out for wild horses, deer, mini buffalo, and goats that traverse the black sand beaches. The underwater topography around Sangeang is heaven for divers. It has so much to offer; from coral outcroppings to sandy slopes. Nitrox is recommended if available. You’ll appreciate the extra bottom time when you lose yourself in the thrill of macro spotting.

Beautiful underwater world around Sangeang

Best Dive Sites Around Sangeang

Here is our selection of superb dive sites in the area. There are plenty more great spots for diving and snorkeling but we tried to limit ourselves to the ones we enjoyed the most.

Hot Rocks Dive Site

A site that appeals to macro and wide-angle enthusiasts alike. Underwater photographers will be delighted by the colorful coral ledges and the challenge of capturing nudibranchs only millimeters in length! The site’s most distinguished feature also happens to be the most accessible. At 3 meters, you’ll find a sandy patch where hydrothermal vents release a constant stream of bubbles. The surreal experience feels like you’re diving in champagne. From 18 meters on, there are gorgonian fans where pygmy seahorses have been spotted. This site also features abundant black coral that is generally not found above 40 meters, elsewhere in the world.

Sunsets and Volcanos on a Private Charter

Diving at Black Magic

Another black sand slope that is covered by coral growth goes down to 30 meters. In general, the bay is calm and serves as an ideal surface interval stop. Due to the impressive visibility, snorkelers can share in the same wonders as their diving counterparts. Common sights include estuary seahorses, leaf scorpionfish, and demon stingers. Of note are the squarespot anthias found at depth and the saw blade shrimps in the black coral.


The island is uninhabited except for a small fishing settlement next to Bonto. If you’re in search of nudibranchs, this should be your first stop. Shaun the sheep sea slugs (Costasiella sp.) are often spotted on green algae of the Avrainvillea species. Consisting of a gentle slope punctuated by coral outcroppings, you’ll find that sharp eyes and a slow pace are the key to uncovering Bonto’s treasures. The site is a favorite of mimic and long-arm octopus. frogfish, mantis shrimp and ghost pipefish.

Octopus sightings around the secret dive spots


A deeper diving site. The sandy slope reaches down to 31 meters, below which stands a drop-off. Black coral is abundant here, clustered on the sand off the wall. Another prominent feature is the sea whips, most of which have gobies living on them. Keep an eye out for orangutan crabs hiding in bubble corals, hawkfish amongst gorgonian, and ornate ghost pipefish. Be sure to check the large barrel sponges for hairy squat lobsters.

General tips for diving in sangeang

As with most muck sites, good buoyancy is critical. It’s easy to inadvertently silt out an area if you don’t practice situational awareness. Practice your frog kicks and work on perfecting your trim. Pointer sticks are a great tool for photographers to steady themselves in mild currents. The temperature of the water tends to be warmer than other dive sites around Komodo. Ranging between 25–28 degrees, a 3 mm full wetsuit is usually enough exposure protection. Add a hooded vest or neutrally buoyant sharkskin rash guard if you chill easily.

Majestic Volcanic formations

What about safety?

While volcanic activity occurs with greater frequency in Indonesia, conditions around Sangeang have held steady since its last eruption. Indonesian authorities are vigilant in their monitoring of volcanic activities. Through apps, advance warning systems, and multi-agency oversight, risks are managed. Of course, travel insurance is always recommended, regardless of your destination. Barefoot Yachts Indonesia can advise you in terms of selecting the right policy.

Why choose us for your diving trip to Sangeang?

Api Sangeang still flies under most diving radars because only selected operators know of its existence. Only a few of them are familiar with the locations of the beautiful dive sites. We provide our guests with honest and tailored recommendations for a Komodo liveaboard itinerary that includes unforgettable experiences like Sangeang.

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