Getting into Blackwater Diving… The images are what immediately grab your attention – seemingly alien creatures lurking somewhere out there in the dark of night. Long after most people have called it a day!

What are these creatures and why are they there? How does it work? Was it all just another clever marketing gimmick to suck you in. Or was this thing something really new and compellingly different?

After a lot of discussions with people I trust it seemed clear that I just had to give it a try. And so at the end of January I took my seat on the Qantas flight to Manila in the Philippines, as I made my way to Anilao – Southeast Asia’s blackwater diving capital.

Getting into Blackwater Diving – What is it?

Also known as pelagic diving, blackwater diving is basically night diving on steroids… Sites for traditional night dives are typically chosen because they are in a relatively shallow area, that is protected from the elements and provides a reasonably safe location to be underwater at night.

Blackwater diving locations on the other hand are the complete opposite. They are in open water where there are currents and well away from land with depths of more than 200m!

Why, you may ask… Well, that’s where those strange creatures are to be found as they rise from the depths once the sun has gone down. The actual dives are typically conducted in the 15-25m zone, but the occasional foray deeper does happen when a special visitor appears!

Getting into Blackwater Diving – Why are the Creatures There?

In much the same way as many of the most special underwater experiences involve entering the water during annual aggregations. Such as South Australia’s Giant Cuttlefish mating or Tonga’s Southern Humpback migration – blackwater diving is all about the Diel Vertical Migration (DVM).

Virtually unknown outside of the scientific community. DVM was first described by the 19^th century French naturalist Georges Cuvier, who noted that a type of plankton called daphnia appeared and disappeared on a diel (daily) pattern. But DVM is not just another migration… In terms of biomass, it is considered as the largest synchronous movement of creatures in the world. And it happens every night, in every ocean.

So intense is that vertical migration that during WWII, it was detected by the US Navy using sonar and initially interpreted as attacking enemy submarines. But further testing established what was then called the DSL (Deep Scattering Layer), which we now know as the DVM.

DVM for Dummies…

Each night, as the sun slips below the horizon, an incredible phenomenon unfolds beneath the ocean’s surface.

Billions of tiny animals, primarily zooplankton such as small fish, shrimp, and jellyfish, along with the juvenile stages of larger creatures, embark on an upward migration from the depths towards the surface.

While the exact reasons for this nightly migration are the subject of many theories. The primary belief is that these creatures ascend to feed in the food-rich surface waters.

And they do it at night, when light is scarce, because they are less visible to predators that rely on light to hunt. Theories surrounding the reasons for this migration include circadian rhythms, temperature changes, prey abundance, and predation risk.

Then, as dawn approaches, the creatures descend back to the depths. But will return and repeat this nightly ritual at dusk in an intriguing cycle that superbly illustrates the intricate balance of life beneath the ocean’s surface.

Nature’s Carbon Pump

The abundant food source in the surface layer of our oceans which drives the upward migration of zooplankton is called phytoplankton. Often referred to as the ‘plants’ of the plankton world. Phytoplankton sits at the very bottom of the marine food chain. And scientists classify it as a “primary producer” that is critical to life as we know it.

Phytoplankton thrive at the ocean’s surface. Because they can absorb sunlight and use it, in a process called photosynthesis, to convert carbon dioxide into glucose and oxygen. Thus, both organic (from the atmosphere) and inorganic (pollutants from fossil fuels) carbon dioxide is removed. Glucose is created as an energy source and oxygen is produced (as a by-product) and released into the atmosphere.

Individually phytoplankton absorb microscopic amounts of carbon dioxide and release equally small amounts of oxygen, but size matters… There is so much phytoplankton in our oceans that the total amount of absorption and release is at least equal to all of the plants and trees on land.

So, what happens to the absorbed carbon dioxide? Zooplankton are herbivorous and consume phytoplankton in vast quantities. Effectively ingesting the carbon dioxide and on return to the depths each morning they release it as organic waste to become part of the ocean floor.

One theory about why DVM happens at night is that phytoplankton can use the daylight hours in relative safety to photosynthesize and multiply. Nature’s way of ensuring the basic building block of the marine food chain remains robust and fully functional.

Getting into Blackwater Diving – How it Works

There are a few versions of blackwater diving… Starting with the original one pioneered in Kona, Hawaii. Where (as I understand it…) a lighted “downline” is used with video lights performing the primary function of attracting the creatures.

But you are tethered to the downline and cannot go off-piste, even if you wanted to. Plus, you have to be careful not to get entangled with other tethered divers. And your reach is obviously restricted to the length of the tether. So you have to hope the critters come within that reach.

Another version is called the “bonfire” and is apparently done in much shallower water with a powerful light secured to the bottom and shining upwards.

The third version of blackwater diving (the one I experienced) resembles the Kona method but offers greater freedom of movement. This innovative approach was developed by Mike Bartick of Crystal Blue Resort (CBR) in Anilao. Drawing from his extensive experience in adapting blackwater diving to local conditions.

Central to this method is the ‘pumpkin’… A plastic orange buoy that supports the downline and features its own video light. The 25-meter-long downline is weighted at the end and equipped with powerful video lights every 5 meters to attract plankton and the intriguing critters that follow.

The pumpkin drifts with the current. But is not accelerated by surface wind, as happens if the downline is secured to the boat. So divers in the water can easily keep up with instead of being left behind in the dark!

The video light on the pumpkin ensures visibility for the boat crew, who maintain a safe distance while following the divers. Additionally, the lights along the downline serve as reference points for divers in the dark waters below.

The First Dive…

It starts off with a 19.00 departure from CBR and it can take up to an hour to get to the area to be dived. So by the time the engines are stopped it is well and truly dark. The crew immediately start to prepare and deploy the downline, video lights and the pumpkin. And then its time to get in the water!

It’s hard to properly describe how you feel on that first dive, but “strange” probably sums it up best! The combination of being in open water in the compete dark of night with the downline lights as the only visual point of reference is quite challenging. But what really plays with your head is the Stephen King-esque imaginings of what is out there in that darkness…

Then there is the challenge of trying to photograph what you do see. And I will cover that in a dedicated article, but the Readers Digest version is it’s no easy feat!

A time cap of one-hour applies to each dive. And you need to surface near the pumpkin and then signal with your torch, as you rotate at the surface, so the boat crew can see that you are up. Initially you can’t see the boat, so hearing the engines as it makes its approach is a very reassuring sound. For safety reasons, divers swim away from the pumpkin to be picked up by the boat. After each dive, there’s a one-hour surface interval before venturing into the darkness once more.

It’s not uncommon to return to CBR around 01:00 in the morning. Which is why I think of it all as the Anilao Night Shift…

Getting into Blackwater Diving – Is it Safe?

Blackwater diving is not something you would consider doing with “Doug’s Discount Diving”… As you are definitely near the effective limits of recreational diving. So it’s imperative that you do blackwater diving with an operator that really knows their stuff . And, most importantly, has the crew to support it. Plus, you also need to be a confident and competent diver with excellent buoyancy control, good self-awareness, and a strong sense of adventure.

I was in Anilao for a total of nine diving days. But the first three days was focused on regular day diving with the general critters the area is known for. Then on the evening of the third day I did my first night shift and simply did not bother with the day diving after that. It took me till the fourth night shift to start to get it… And after that there was no looking back. While I was very much out of my personal comfort zone during those first three days but never actually felt unsafe or in danger once. Strange yes, in danger no – so yes, I think it’s safe!

In Summary

Reflecting on my experience in Anilao, I realize that blackwater diving was an itch I didn’t know I needed to scratch… Until I did. To be more precise, it’s blackwater diving combined with underwater photography that truly captivated me. The unparalleled visual opportunities it offers are unlike anything I’ve experienced before.

I’m already plotting my return for another series of Anilao night shifts. Plus actively scouting other locations to indulge in this truly compelling form of diving.

Getting into Blackwater Diving X-Ray Article

The excellent global diving magazine X-Ray just published a seven-page article of mine on Getting into Blackwater Diving and you can use the link to download a copy from their site.