Blackwater and Bonfire Night Diving at Lembeh Resort, North Sulawesi


Critters at Lembeh Resort Dive Centre Manager Brigitte Gassner is a huge fan of blackwater and bonfire diving where she is able to spot and photograph critters at their larvae stages. Many of the sightings during these dives are critters which are unseen by the majority of underwater photographers and scuba divers. Brigitte has even been able to spot a paper nautilus at one of Lembeh Resort’s closest dive sites.

Brigitte is passionate about sharing these new diving experiences with guests staying at the luxury Lembeh Resort located on the banks of the Lembeh Strait. But what is bonfire and blackwater diving and how is it different to other night dives?

Image: Brigitte Gassner

It all Starts with Plankton

There are two types of plankton; zooplankton (which is animal based) and phytoplankton (which is plant based). These two forms of plankton drift with the ocean currents and are the source of all marine life. The word “Plankton” is derived from the Greek word “Planktos” which translates into English as “drifter” or “wanderer”. Did you know that in one teaspoon of sea water there are literally billions of life forms?

What is Blackwater and Bonfire Diving?

Blackwater diving takes place over deep water, away from the reef. In Lembeh, blackwater dives usually take place in the middle of the Strait. Bright lights are suspended in the water column at various depths up to 25 meters. The lights attract plankton in the water column which in turn attracts intriguing and rarely seen larvae stage critters.

Bonfire diving takes place at shallower depths on the reef or sandy slope – in Lembeh, there is no shortage of suitable dive sites. Bonfire diving is also based around the use of bright lights to attract plankton and both larvae stage and more mature critters.

Image: Lilian Koh

Blackwater and Bonfire Underwater Photography Subjects

The most iconic blackwater and bonfire dive critters include crustacean and cephalopod larvae and of course the paper nautilus which, to many, is the ultimate of all critters. Other common subjects include jellyfish and other critters which drift freely in the open ocean. Many larvae stage critters do not yet display any coloration and are often translucent as they are still in the early stages of development. Both types of diving feature a lot of critter behavior spotting and imaging opportunities.

Jellyfish are often behavioural hotspots, look out for jellyfish playing host to a range of species from tiny amphipods through to jackfish. The jackfish will enter the jellyfish and use it for protection, it’s often possible to see the jackfish going in and out of the jellyfish as it exits it host to breathe before re-entering.

Image: Lilian Koh

Blackwater and Bonfire Photography Techniques

Blackwater and bonfire photography require using fast shutter speeds – typically sync speed, as you are capturing images of larvae which is moving. A fast shutter speed will help to “freeze the action”. Shooting with a small aperture, which gives more depth of field, allows for more of the critter to be in focus as opposed to only a small section which is closest to the lens.

Best Times for Blackwater and Bonfire Diving

It’s technically possible to blackwater and bonfire dive at any time but Brigitte says the most abundant dives are around the new moon – up to 4 days before and 3 days after. Around the new moon there is little moon light so the bright dive lights become more active. When there is a full moon there is already light on the surface so the level of activity is dispersed and less centered around the dive lights.

Image: Lilian Koh

Lembeh Resort

Are you planning a trip to North Sulawesi? Lembeh Resort not only offers marine biology and underwater photography trained dive guides, luxury accommodation and exquisite dining – they are also committed to sustainability and are the 2019 winners of the prestigious Blue Green 360 award for Dive Operator of the Year awarded at ADEX in Singapore.

For more information about Lembeh Resort take a look at their website 

Sarah Wormald

Sarah Wormald

Sarah Ann Wormald is a writer and PADI Master Instructor with a passion for underwater photography and conservation. Sarah is the author of “Diving in Indonesia” and “Diving in South East Asia” (Tuttle Publishing). With over 20 years of diving experience, Sarah has dived all over the Indonesian Archipelago and South East Asia. Find out more at

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