have in common is that they are conducted with very bright lights attached to a downline in the water , primarily to serve as a visual reference point for the divers , and also to attract plankton .
A few years ago , this was virtually unheard of , with only a handful of specialist photographers venturing out to do it , but in recent years it has gone mainstream . Increasing numbers of dive centres now offer it .
Just why is blackwater diving so popular ? Well , it gives divers the opportunity to spot other-worldly , larval stage and juvenile sea creatures that would otherwise remain deeper than the limits for recreational diving . What was once regarded as a rare sighting has , in some cases , become commonplace . There ’ s also an element of thrill and excitement doing something completely new and unknown , waiting for creatures to emerge from the darkness .
Blackwater diving takes advantage of the diurnal migration , also known as the diel vertical migration ( DVM ). This is the largest synchronous migration on the planet . It occurs nightly when planktonic , larval and juvenile stage organisms move up to the epipelagic zone ( shallow water ) during the night and then return to the mesopelagic zone ( twilight zone , starting at around 200m depth ) during the day .
Since the discovery of the DVM in the early 1800s , this migration has been observed globally in almost all bodies of deep water , whether marine , freshwater or brackish .
There are many theories as to why these organisms migrate vertically , the primary one being to feed in the shallower waters , where food is more available . By migrating under cover of darkness , creatures are less likely to be eaten , as many predators are either inactive at night , or depend on light to find and catch their prey . The migration has even been recorded during solar eclipses , triggered by the sudden decrease in light .
Jellyfish with jack and argonaut
A tiny seahorse grasps onto a piece of plastic
The rules of Blackwater diving
Blackwater dives are conducted in different ways around the world and may differ by resort or dive centre in the same area . At Crystal Blue Resort ( CBR ) in Anilao , Philippines , the setup is tried and tested . Mike Bartick , general manager and photopro , pioneered blackwater diving in Anilao , which has set the standard locally .
The boats go out after dusk when the skies are already dark , and normally return
between 10:30pm and midnight . When the boat arrives at the dive site the crew begin to prepare the gear . This consists of a large , circular orange surface buoy illuminated by a torch , referred to as the ‘ pumpkin ’ for obvious reasons . A weighted 22m rope is attached to the buoy , with torch attachment points weaved into it at 5m intervals . Eight 15,000 lumen underwater torches are attached , two every five metres . The line and buoy are deployed into the water , over an area of deep water , often more than 800m . The setup is left to
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