Dealing with down currents

[CapitanBlack]

Maldives has very strong current of all kinds - regular, up, down, washing machines... Diving in kandu (atoll's channels) always mean strong currents.

 

[redacted]

Might be because more people dive there than anywhere else on the planet?

The possibility of down currents is yet another reason to keep a decent amount of gas in reserve.

The type of down current that takes 2 experienced and well respected dive professional working in Cozumel down to 300 ft, runs at least one OOG, and puts them in the hospital in very serious condition would likely be the last dive for some in a group of typical vacation divers led by a single DM. I hope we learn more about the where and how of this incident soon.

 

[ianr33]

The type of down current that takes 2 experienced and well respected dive professional working in Cozumel down to 300 ft, runs at least one OOG, and puts them in the hospital in very serious condition would likely be the last dive for some in a group of typical vacation divers led by a single DM. I hope we learn more about the where and how of this incident soon.

Agreed,but I would be very interested to know how deep they were when they met the down current.

 

[TwoBitTxn]

The wall section in Coz that I have heard most connected with down currents is Santa Rosa. Not saying that is where the most recent accident occurred.

This is one of the reasons I hear commonly given outside of Coz for Santa Rosa not being a novice dive site.

 

[redacted]

The wall section in Coz that I have heard most connected with down currents is Santa Rosa. Not saying that is where the most recent accident occurred.

This is one of the reasons I hear commonly given outside of Coz for Santa Rosa not being a novice dive site.

Yes, and I understand it is supposed to be quite beautiful at 130+.

 

[DazedAndConfuzed]

I remember encountering downcurrent on Cozumel's Cedral Wall, where I must have drifted 20-30ft below the group without just by going what I felt like straight ahead. Then there was this section where the wall curves toward the island, but the current didn't, so we ended up being 40 ft from the wall, and next thing I know, current pushed everybody far far from the wall. I could see the DM around 80 ft farther than me, another group maybe 50 ft beyond him, and I could barely make out the wall in its hazy distance, all at the same time there is a downcurrent given that I had to constantly kick hard to stay at try to reach the height of the top of the wall. Oddly enough, after 10+ minutes or so, current carried me back to the wall. Seeing the wall and another group of divers gave me the biggest relief.

Some other person in another boat got caught in the downcurrent, must have panicked and shot up, came up with blood coming out of their nose and was sent back down.

 

[Diver0001]

I know I have read information on how to deal with a down current, but doing a search I cannot find anything

So,

How do you recognize the start of a down current?

The ones I've seen can be recognized by looking at fishes an plants. I saw a downwelling on a reef in Egypt that was so strong that all the fishes were pointing straight up and swimming like hell.... Grasses or other flexible plants can also give you advance warning that you're about to hit one.

How do you deal with one while you are in it?

In theory you're taught to swim perpendicular to the current. If it's along a wall, which is where I've seen them most often, that might mean reversing course or swimming away from the wall.

In practice, use your BCD to help you not sink too far and as a last resort swim to the wall and grab on. I've been in one that took me from 8 metres to 22 metres in a few seconds so they can be very strong and in some cases you might not have much time to weigh your options. My first impulse would be to use my BCD and swim away from the wall, which is how I got out of the one I just mentioned but on the same token, if it were much bigger I might have been dragged down much further before escaping it.

Local knowledge is indispensable here... Local divers will know how a particular reef should be approached if there is a possibility of downwellings. Ask around for advice/ideas. Every reef is different.

Any where else?

I've seen them in offshore reefs in Egypt and in certain places on the West coast of Canada, in both cases caused by tidal flows.

R..

 

[Quero]

I know I have read information on how to deal with a down current, but doing a search I cannot find anything
So,
How do you recognize the start of a down current?

Watch the fish. Generally a down current is like a river of water within the greater mass of water. Look ahead to see what the fish are doing. Smaller fish will always head into the current, so if you see a few meters ahead of you that the fish are pointing upwards and appear to be struggling to stay in place, you are heading towards a down current. If you get caught in a particularly bad one that flows forcefully straight down, you can observe your bubbles to see where they are going and how far down they are taken before they begin to rise again.

How do you deal with one while you are in it?
How do you get out of one (preferably alive)?

Down currents are often localized, meaning that if you spot one ahead of time, you can swim around it by moving away from the wall and back towards it in an arc. If you find yourself caught in one, do like the fishies and point yourself upwards. I usually recommend NOT inflating your BCD if you can avoid it because that only gives the current a larger area of your body to push against, and once you're out of the current, an over-inflated BCD can cause its own problems by dragging you unexpectedly upwards as soon as the current dissipates.

Once you are actively in a current, it's best to stay near the bottom or the wall where the water moves a little more slowly. If you can hold on to the wall or bottom and drag yourself along, do so, but try to go at an angle to the current rather than straight against it. Even a 45° angle will help you move across and upwards through a current washing straight down a wall.

It's always a good idea to carry two or more signaling devices when you are diving in high-current areas. That way if you are separated from your group you can be spotted once the current has released you or you have worked your way free of it and have surfaced. I always have a DSMB, a whistle, a mirror, and a small dive light with me. Some people carry dye packs.

I know Coz has periodic issues with down currents. So does the Galapagos. Any where else?

Are there dive destinations or dive sites where down currents (or other currents) can be so severe that divers should be warned and maybe think twice before attempting such dives?

Early in my dive career I went to Cozumel. At the time I was amazed at the currents, but since that time have experienced quite a number of more exceptional current dives. A few years ago I dived Galapagos, specifically Wolf and Darwin, where fierce currents can be found. The boat I sailed on required a minimum of 60 dives to join the charter because of this.

The most severe downcurrents I've ever encountered were at Nusa Penida near Bali. These are caused by the Indonesian Throughflow which transfers water rapidly from the Indian Ocean to the Pacific Ocean through the little gaps between the long string of the Indonesia Arhcipelago (like the water rushing out of the flood gates of a dam from a reservoir to the river below). Similarly, I've just returned from a trip to Komodo where the currents are famously wicked and are also a product of the ITF. There are dive sites at Komodo named specifically for the effects of the currents at that place. Two of my favorites were Rollercoaster and Shotgun. You can imagine the rest. I believe that a minimum of 60-100 dives and confidence in dive skills should be required in order to attempt these particular sites as well as other signature Komodo sites famous for currents (and there are many).