Downward currents?

A couple weeks ago I was diving with a buddy from my club, one of my first times doing so outside of our organized club dives and at a location I'd never been. The site itself was great, and the person I went with was a great buddy. While down at about 55ft we hit a really strong lateral current which would have been very difficult to fight. It swept us along quite quickly which we took advantage of for a bit, then ascended about 10 to 15 ft to escape it. All went well and we finished our dive at a more shallow depth, finished up and headed home.

I'm currently AOW with 36 dives, though I did my OW 3 years ago. If they mentioned anything about currents then I've long forgotten it, as they've never been an issue at the spots we usually dive. My biggest concern (especially here in BC, where there are some tremendous vertical drop-offs) is hitting a downward current and not knowing what to do. Do these exist? If so (I'm almost positive I've read about them here before), what's the procedure to escape them calmly and safely?

I've never experienced anything too bad but the idea is to not fight it but to move out away from the wall. The down current is just due to strong currents hitting the wall and being forced down. If you know of such a site generally it's a problem only on a flood or an ebb and you just need to find out which for that particular site.

I love the wall dives at Whycliffe Park (The Cut) and at Ansell Place. I've never run into down current there however.

There were 3 of us diving on a wall, we dropped into the water on top of the wall but when the bubbles cleared we could not see the wall or any visual reference as to where we were! My ears started to tell me I was decending rather fast, the same the other 2 divers! On checking my computer, the depth readout was like a slot mechine, we were really going down fast! Upon realizing what was happening, we all put air into our BCD's and stopped the decent, at 55 meters, this depth in less than a minute! WOW! We started our decent nice and slowly and took 10 minutes to get to the surface with safety stop! When we got our position, we were more than 1 km from our entry point and a half km from the shore! Bubbles were still following us to the surface!
The German Diver with us said in good fasion, You have some very interesting currents here i see!
What an under statement!

The next dive was the opposite, during the dive the current came upwards, we were hanging onto the wall, fins upward getting pounded by sand and gravel from the depths! Luckily, the current was pulsing so we could move upwards in between pulses until we got over the wall where there was little current!

After such wierd dives we retired to the bar and fully enjoyed the late afternoon!

This happened on the Tinto Wall in Sarangani Bay!

Thrillhouse:

I'm currently AOW with 36 dives, though I did my OW 3 years ago. If they mentioned anything about currents then I've long forgotten it, as they've never been an issue at the spots we usually dive. My biggest concern (especially here in BC, where there are some tremendous vertical drop-offs) is hitting a downward current and not knowing what to do. Do these exist? If so (I'm almost positive I've read about them here before), what's the procedure to escape them calmly and safely?

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Ok, what they teach you in your OW course about currents is this:

1) swim into them at the start of a dive
2) don't wear yourself out in a current. If you get exhausted and need to rest grab something, find an outcropping with calm water behind it, stick your knife in the bottom and hang on or whatever and take the time to rest... alternatively, if you can, just drift with the current and/or abort the dive.

As far as I know, most instructors don't handle what to do in a down-current unless it's a common local occurence. I've dived all around the lower mainland and a bit on Vancouver island and I've never encountered a down-current there anywhere.

I *have* encountered them in Egypt on deep offshore reefs under the right conditions, namely when the underwater current flows perpendicular to the reef. This creates much stronger current and up/down wellings than the bit of current you can get with a tidal flow. To get the kind of downwellings to be afraid of it really requires a lot of flowing water (like an open ocean current) running perpendicular to some deep dropoff. You *might* be able to get that on certain locations off the west coast of Vancouver Island around Uclulet/Tofino or the Queen Charlottes but I wouldn't expect it to occur anywhere on the eastern side of Vancouver Island or in any of the inlets. At least, in my experience they don't occur there....

The idea of moving away from the reef is basically right because the currents are stronger the closer to the reef you get but I've also seen down-currents that were so strong that once you start swimming off the wall you'd have to swim well away from the reef into the blue and then abort your dive and hope they find you back on the surface again. In Egypt last November I made a dive on Elphinstone like this in a strong reversed current. The downwellings were getting dangerous. Our group consisted of experienced divers and we stuck close to the reef and used outcroppings to duck out of the current and to re-group a couple of times during the dive. I was personally only able to control my position in the water within a 10 metre band... LOL. Another group that went into the water at the same time couldn't handle the current and got in the downwellings, had to swim off the wall and surface.... they were found 1km away (I heard), which is an enormous distance to get blown off the reef during a single dive.

The lesson/message here is to get lots of experience diving in tidal flows and to consult with local divers so you can avoid locations that are prone to downwellings for the time being.

R..

Sensing them is the first step. Watch for the positioning of critters and fauna, watch how they move and the way they are being blown or swept. As you get more experienced, you'll likely first sense your undesired depth changes by minute variations in the character of light from above.

It's just as easy (most of the time) to escape vertical currents- just as you did with lateral currents... move away from them.

With the lateral currents, you learned to ascend (or descend) and that quite often fixes things quick.

Same thing with downwellings (or upwellings), aka vertical currents. They don't just come out of nowhere and appear like "wind sheer" does to pilots. They are usually found in heavy current areas off of walls or other vertical structures.

Just swim away from these structures and you'll soon be out of such currents. You may then have to begin this portion of your dive "on instruments", navigating expertly into the blue. This is yet another "advanced diving skill" that becomes a task-loading issue, just after dealing with the vertical current.

"Advanced Diving" is any new stimulus, quite often compounded into task loading by multiple new situations. Always check experts for local condition reports and specific micro-currents, etc.

RoatanMan:

Sensing them is the first step. Watch for the positioning of critters and fauna, watch how they move and the way they are being blown or swept. As you get more experienced, you'll likely first sense your undesired depth changes by minute variations in the character of light from above.

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Yeah, this definitely works in the tropics. On the dive I mentioned above you could see ahead of you exactly when you were going to get nailed by the down-welling because all the fishes were pointing straight up and swimming like crazy.... then 2 seconds later ... whump! LOL These dives can also be alot of fun if you don't mind a bit of risk...

Getting to the point, around Vancouver there generally aren't enough schools of small fishes to really see it coming. A lot of the fishes either don't school, or they're fairly big or lay on the bottom most of the time. Also, due to algae blooms most divers tend to dive under them where the light is limited. I think *if* you were to hit a downwelling in those conditions that there's a good chance of it catching you off guard. YYMV

R..

There is a dive in Komodo National Park that they call "Washing Machine." (I'm sure there are others with the same name.) From the skiff we could see clear signs of turbulence on the surface where our dive would end: eddies and flat areas with no ripples. We motored a short way further and dropped in to a gently sloping reef and a mild current. Following the instructions from a detailed dive briefing, we maintained our depth around 50 feet as we approached a clearly defined ridge. The current accelerated noticeably as we neared the ridge and all the fish were oriented towards the depths. At the instant we traversed the ridge a strong vertical current swept half of us up to 25 feet and the rest all the way to the surface. Three of us, including our guide, took refuge in a little niche in the reef. It was amazing that you could actually stick an arm out from our little alcove and feel the fierce current outside. Just a few meters further along on the reef the current was equally fierce in the opposite direction, and we swam into it and had a quick elevator ride down to 90 feet, where 3 reef sharks swam in a circle and the current petered out. It was a great dive and a great experience, but if it had happened without any warning it would have been scary as hell. As it happened though, it was more like an amusement park ride.

vladimir:

There is a dive in Komodo National Park that they call "Washing Machine." (I'm sure there are others with the same name.) From the skiff we could see clear signs of turbulence on the surface where our dive would end...

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Our DM's actively searched these out for us in the Philippines (Puerto Galera, Hotel Atlantis). Looked like whitewater. Right out in front of the place, as well as in Batangas Channel. Screamers.

On Isla Verde, the day trip to the ENE, there were underwater waterfalls. One had a 80 gallon cement drum with metal cable kiting out into the current. Grab on, inch out, and hang on a bit tighter. Nuckin' futz.

Want it in the Caribbean? Coz is for kids. Try Tobago Speyside and go for a ride along "African Express" (make the turn or the next stop will be Nigeria). They also have a "Washing Machine" as well as "Heart Attack".

I got bored with roller coasters long ago

These happen with some frequency in Cozumel. I was caught in a strong one once and escaped it by doing exactly what is taught in Knowledge Review 3 in PADI training--swim perpendicular to the flow until you are out. It works the same at depth as at the surface. The current was essentially a waterfall whose edges were invisible, so I got out of it before too long.

When I teach KR 3, I do mention this to my students.

There are times when that will not work easily because the flow is too wide or two powerful. That is very rare, but it does happen. In that case, treat it the same as if you were negatively buoyant--put more air in your BCD as you swim to help overcome the flow. Be ready to dump it in case you suddenly emerge from the current.

boulderjohn:

These happen with some frequency in Cozumel. I was caught in a strong one once and escaped it by doing exactly what is taught in Knowledge Review 3 in PADI training--swim perpendicular to the flow until you are out. It works the same at depth as at the surface. The current was essentially a waterfall whose edges were invisible, so I got out of it before too long.

When I teach KR 3, I do mention this to my students.

There are times when that will not work easily because the flow is too wide or two powerful. That is very rare, but it does happen. In that case, treat it the same as if you were negatively buoyant--put more air in your BCD as you swim to help overcome the flow. Be ready to dump it in case you suddenly emerge from the current.

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Barracuda Reef has some too--we dove it a few weeks ago & hit a mild one---everyone(all 5 of us) just 'rode it out'---dropped us maybe 25 feet but we were diving steel 120's & knew we had enuff air to(hopefully) 'take care' of any deco we ran into---none(deco) was encountered...