Down current, downcurrent, down welling, vertical udnerwater current spearfishing freediving

  • ..have to be careful while diving around the rocks because of currents which push you like a wisp of straw to the depth!

    Down current, downcurrent, down welling, down draft, in other words a vertical underwater current that runs down into to the depths.. of all the risks associated with freedive spearfishing this one really scares me. Avoiding a blackout, getting tangled with line on the bottom, being run over by a boat or attacked by a shark, all seem manageable in comparison. Down current is something I've never experienced and so only know about it from others accounts. To me it's the ultimate worst thing that can happen freediving, getting sucked down to depth near the end of your breath hold. Most of us know you can't fight a strong current even on the surface.

    How do you deal with a down current? Is there a warning it's about to happen? Is there time to react? How deep will take you? Once you're caught what to do to get out?

  • I've dove around some wash rocks that get surrounded by super aerated water when ever a set wave washes over. The lack of buoyancy from the aeration can feel like a downward current. Probably not the phenomena your asking about.

  • I understand the idea of aerated water. But if it happens together with a wave how do you know what's happening is not backwash from the wave?

    Good question. I'll video the spot next time I pull some scallops. Its kind of a mellower version of the "diver taken in undertow" video above except I pop up with some dinner plates.:)

  • That is some scary stuff. I dont think I've ever experienced a down current to the degree of those videos, but there are areas where I dive that have what I describe as "heavy water" where ascending feels like it takes ages.

    Thanks for this very important information.

  • Same here. The first time I heard about “the undertow” was when I was watching “Finding Nemo” with my daughter. Scary stuff you don’t hear much about

  • I also want to add some videos here which explain better the kind of currents and type of diving and quarry which Kosta was experiencing. I've dove those spots many times and I have seen/experienced currents similar to this on occasions.

    This clip from Perrin James shows the kind of currents. The longer film shows some of the spearfishing in these kind of areas.

  • This video demonstrates one kind of downcurrent clearly. I've seen downcurrents that were more like whirlpools like a toilet bowl flushing. These were usually in the Lee of a reef structure or small Island. The downcurrent in this video is more likely what Kosta may have encountered.

    Water is like Air when it's flowing in a current. A large volume of water is pushing in a current along a shallower section of reef. It's like the water is under pressure, that is why it is moving. As it hits a drop off, there's no longer that bottom holding the volume of water so it spills into the abyss like a waterfall. In this video, if the diver had swam in towards that cliff, he would have been in the shadow, under the waterfall. But where he was he was catching the force of the river spilling down onto him. He could have swam into the cliff and hugged it and then punched through and up. Alternately he could have angled off away from the Waterfall and the downcurrent would have been less intense. In some cases, the area to the left or right may have also been less severe.

    When you are dealing with currents it's important to try to take a birds eye view and visualize the landscape underneath. Then to try to understand how the water will be reacting to the different contours. Try to visualize the eddies the current flow. Often you can move just a little in one way or another and avoid the brunt of a current or use it to your advantage rather than disadvantage. For example. If there is a current raging down a shoreline you can hide from it in some contours, like a big rock will be a shelter just like it would from the wind. If there is a current raging down a shoreline, often you can hug very very close to that shoreline and there will be a reverse current or atleast a very lessened current in that few feet.

  • Jon, Dan, this thread and these video examples are truly eye opening! This is a hazard that many freedivers and spearfishermen are totally unaware of, at least where I live (Hawaii).

    I like the idea of knowing the bathymetry of the area you are diving to better understand where water is moving. I can also assume that areas where there is a large tidal shift are more prone to such phenomenon, as well as areas where two currents or even bodies of water converge (like Cameron Kirkconnel's example of the Pacific and Indian ocean emptying into one another. All of this is good information to prepare divers and prevent accidents from occurring.

    I assume that where there are down currents this strong there may be up currents with similar strength, (harder to descend) or is the dynamics of these currents primarily based on gravity, and these up currents I am describing result in upwelling.

  • Hi Akira, I haven't seen these kind of currents in Hawaii. But over here everything is so darned deep and the water is clear so weighting and dilligent buddy system becomes so important. Sure, I've seen upwelling. As a current comes from the deep onto a shelf. the reverse..

  • Eric (Freedro) tells his experience with a downcurrent in Panama.

  • I use the same floatline setup as spearfishers in Norway; the spearfishes use the floatline connected to the belt at all times, due to the strong currents. Down-welling is less problematic if you are able to drop your belt and pull your self back to the surface. In that way the floatline acts as your lifeline back up to the surface. In the belt I use a quick shackle, easy accessible for quick detachment.

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