Diving with Volcanoes

Exploring the volcanoes of North Sulawesi
By Paul & Lisa Hogger


Whether active, dormant, or extinct, volcanoes are a fascinating and occasionally volatile feature of nature. One country stands out as having the most active volcanoes on the planet, and coincidently some of the best diving – Indonesia.  Indonesia’s far northern archipelago gives divers opportunities to dive in close proximity to volcanos.

The Sangihe Islands are a rare trifecta of dives; a lucky individual can dive on an active underwater volcano, the base of an active volcano and an extinct volcano with its series of old lava flows that extend down to well below recreational diving depths.

Each dive is different, unique, and a little intimidating. Volcanoes can be a challenge to dive, let alone photograph.  

Mahengetang Active Underwater Volcano

The Mahengetang Active Underwater Volcano is the most difficult of the 3 to dive and photograph – mainly due to its remote location and in-water conditions. Despite being relatively close to a small island which offers some shelter to wind and swell, the currents are strong in the area and the pinnacle must be dived on the slack tide.

It’s interesting to note that a prior scientific expedition had reported that the peak was 5m/16ft below the surface. During our dives there 4 years later, the rocky peak had risen and had broken through the surface.

All around the peak are hundreds of cracks in the rocks allowing the sulphur bubbles to escape and float upwards. The smell of sulphur at the dive site is very strong, and the water temperature around the volcano is an average of around 35°C or 95°F.  

This excess heat is a little uncomfortable even without a wetsuit but a lightweight exposure suit is still recommended. The upside of the excess heat is the incredible, unusually shaped soft corals and sponges.

What makes the dive frustrating to photograph are the extreme thermoclines at depths ranging from the surface down to at least 35m/115ft. In addition to massive temperature differences, the heated layers create swirling bands of haze that make it difficult to see and impossible for the camera to focus. With all of the layers overhead, available light is also greatly reduced to about half that of a standard dive.

This has wide angle photographers constantly adjusting ISO, aperture, and shutter speeds to compensate for the inconsistent and ever-changing lighting. With models wearing black, the exposures were especially difficult. For subsequent dives, brighter colours were used giving some added safety.

During surface intervals, you can walk around and get a glimpse of life on the small island by watching the locals repairing fishing nets or building large timber fishing boats with chainsaws and basic tools. Although they don’t speak English, they are welcoming and the smiling children will happily follow you everywhere you go.


Ruang Volcano and Lava Flows

Travelling by boat around the Ruang Volcano is stunning.  It’s a single volcano with all sides running down to the water’s edge creating a near circular island with deep water all around. The caldera can be clearly seen and is partially destroyed from the last eruption.

But what is most fascinating are the two large lava flows that start at the peak and expand down the hillside and into the water. The rock is black, rough and very porous making it ideal for hosting corals when underwater.

Like the nearby Mahengetang Volcano, this area also has strong currents but with the lava flows being so wide, it is perfect for drift diving.  The variety of coral is incredible with equal amounts of hard and soft corals as well as ample sponges, sea whips and fans. It’s some of the most diverse coral gardens we have ever seen.

Interspaced between the lava rocks and coral is black sand making for ideal macro photography as well as wide angle.


Karengetang Active Volcano

Karengetang is one of Indonesia's most active volcanoes. From a distance, the constant plume of dense white smoke can be seen rising high into the sky and occasionally, the sight of lava spewing vertically into the air is visible as well.

At night the peak has a constant red glow and is fascinating to watch while anchored in the harbour below during both the day and night.  It does erupt regularly and erupted just 6 months prior and also 9 months after we had visited the area.  The volcano is in the Sitaro Province and the township of Siau is nestled on the water’s edge at the base of this 1870m/6200ft tall volcano.


There are many dives all around the volcano’s base from large coral walls, points teeming with fish, coral, and even a wreck – all of which are on the west coast.

But for us, the highlights were the black sand muck dives on the east coast of the island, in the harbour directly below the volcano.  The macro diving here is superb and in our opinion  surpasses the Lembeh Straights, located around 100 miles south of Siau. The big difference from Lembeh being the lack of crowds, and the deep rumblings of the volcano that regularly vibrate right though you whilst underwater.

More detail and images on Siau’s diving can be found in our “Dispatch from Siau” article.

Volcano Hike

The volcano experience can be topped off on the last “no dive” day with a hike up Karengetang.  The 3 am start is at the discretion of the local volcanologist, and is just the first step of a very physical 15 hour climb that requires an experienced guide, very good footwear, and a high level of fitness. After a beautiful sunrise, walking up through the clouds in the middle of the day, and the views overlooking the bay are well worth the effort.

The area can be accessed from Manado by light plane to Siau, fast ferry, or the occasional dive liveaboard with exploratory charters of the area.

For divers travelling from Manado to the Lembeh Straights or the Bunaken Marine Park, it’s a great way to tack an extra few days diving onto the trip and with the right weather, get a little volcanic diversity to your dive holiday.


Paul and Lisa are an Australian couple originating from Australia’s East Coast. Of their 20 years of marriage they have lived on their private yachts Purranha and Lorelei for 14 years and have been full time sailing/cruising for 9 of those years. Their latest expedition began in 2011 onboard Lorelei with the main purpose to dive many of the world’s best dive locations. To date they have explored 22 countries in the South Pacific, North Pacific and Asia – covering a distance of over 24 000 nautical miles.

They are independent divers and can proudly say that over 95% of their underwater images were taken whilst diving by themselves from their purpose built dive tender on board Lorelei. They are PADI pros and have over 8000 dives between them. Due to the harsh conditions of sailing life, they choose Nikon, Ikelite and Aquatica photographic equipment.

More information and images of their travels can be found on their blog:



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