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June 2012    Download the Entire Issue (PDF) Available to the Public Vol. 27, No. 6   RSS Feed for Undercurrent Issues
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Those Deadly Downcurrents

do you ride it out or react in the worst way possible?

from the June, 2012 issue of Undercurrent   Subscribe Now

Riding along in a current is a great diving thrill, but when it suddenly yanks you upward or downward, the thrill can become frightening, and sometimes tragic. How you react is a matter of life or death.

Subscriber Jonathan Blake (LaVerne, CA) had his first rogue current experience in the Arborek area of Raja Ampat. "I was finning along the edge of a cliff at about 45 feet, enjoying the pygmy seahorses on the sea fans. I was experiencing a little surge, when the downcurrent hit with no warning. At 90 feet, my dive guide and I managed to grab on to a small outcropping of the wall. We saw another diver, a small Japanese woman who probably weighed 100 pounds soaking wet, and her dive guide, holding on to her BC, shoot past us. I thought they were gone for good. While the downcurrent lasted less than 30 seconds, it seemed much longer. Miraculously, the other dive guide and the diver appeared. He had managed to pull her under a crevice in the wall at 120 feet and out of the downcurrent. It happened so fast there really wasn't any time to be terrified. I think discussing during the briefing the possibility that it could happen, and how to react if it did, helped save us from disaster."

David Hill (Ipswich, MA) got caught in a "washing machine" current in Bunaken National Park in North Sulawesi. "I was working along a wall at 40 feet, when suddenly, the current picked up strongly. For 30 seconds, it would howl in one direction, switch to the opposite direction, then howl straight down, then straight up. The current was far stronger than I could swim against. My group was instantly scattered, and I ended up clinging to the wall with two other divers. It was one of the strangest sensations of my diving experience to be looking at my buddy clinging to the wall next to me and watching his bubbles streaming straight down. Eventually we worked our way up the wall to 20 feet, waited until the current was going sideways, and finned to the surface. But even on the surface, the currents and whirlpools were so strong, we were swept in different directions. The three dive boats ran around picking up any divers they could find, then rendezvoused. Everyone was OK, but it was a harrowing experience for some of the novice divers. We checked one poor woman's computer, and found she had started at 40 feet, been blown to 10 feet, sucked down to 90 feet, and then blown back to 20 feet. She was fine, but more than a bit shaken."

"It was a strange sensation to look
at my buddy clinging to the wall
and watch his bubbles streaming
straight down."

Randy Preissig was diving the south tip of Peleliu Island in Palau, which has a strong current that sweeps divers along the northern edge of the island, then makes a 90-degree turn south at the island's tip. "We were warned that the current would 'pick up' as we turned the corner, and that it would be difficult to grab a hold as we swept over the edge -- no second chances. This turned out to be an understatement. I was flying when I turned the corner, as the current went to turbo, and I barely managed to grab hold and stay on the ledge, watching huge silver-tip sharks 'surfing' the current. As they got closer, I dropped off the ledge. I began at about 50 feet, shot some air into my regulator and started gently kicking up. Then I realized I didn't seem to be getting closer to the surface. I was at 140 feet and sinking very fast! I think if I had waited even 10 more seconds to determine my depth, I might not have made it. A wave of fear grabbed me as I realized I would require a deco stop. I put an amazing amount of air into my BC and kicked strongly. When I again glanced at my gauge, I found I had barely ascended! I now kicked like Neptune wanted my ass, and I was just able to overcome the down current, as it slackened at around 70 feet. I was a strong athlete who had run marathons and exercised regularly, so I think most divers would not have survived this experience. I surfaced, fortunately on a very calm day, and the boat eventually found me, miles from the tip of Peleliu. I later learned that two Japanese divers had disappeared at that spot, and that it was no longer being dived -- well, at least for a while."

Going Down Without Even Noticing

Oceans move constantly, with currents coursing through them like giant rivers. Currents are the result of winds, tides, thermally unstable water columns and seismic events, often in various combinations. Most currents run horizontally to the earth's surface, but especially dangerous ones run vertically, toward the bottom or toward the surface. Such currents are often found when a horizontal current strikes the face of a wall and then moves down, up, or both. Downcurrents can also appear when a horizontal current runs perpendicular to a drop off, or where two opposing currents run into or over each other. Marked differences in water temperature and salinity in the water column can also produce vertical currents, but these are generally sluggish and pose no threat to divers.

A downwelling can unexpectedly pull a diver deeper than his dive plan. It may happen so gradually, he may not notice it. Sometimes, however, the current will rapidly drive the diver deeper, occasionally much deeper. In Tobago several years ago, the current yanked a nearby diver from 20 feet to 85 feet in the blink of an eye. If you have air, equalize quickly enough and don't panic, you can probably ride it out uneventfully. A violent upcurrent, however, causes a diver to ascend far too rapidly, perhaps missing a safety stop if not planned, and precipitating DCS. Additionally, if a diver's surprise at the sudden ride upward results in breath-holding, an embolism is possible.

Douglas W. Peterson (Elk Grove, IL) was drifting comfortably along the top ridge of a long reef in Cozumel around sunset "when it suddenly dawned on me that I was being pushed way deeper than I liked, from the top of the berm, down over its side and into the depths. Once I hit 90 feet, I turned back into the current to fight my way back up, but I was getting nowhere. I was just stuck around 90 feet, kicking full speed for my life, all my hoses wrapped in tightly by my arms, and rapidly running out of gas. I realized that I couldn't make it that way, so I just gave up and turned to go with the main direction of the current and let it sweep me along the berm, in line with the original dive plan. I worked to maintain my altitude and not get pushed any lower, but it was easier now because I was no longer kicking into the main current itself. A short while later, the downward push just disappeared, and I was able to slide back up to 60 feet, calm myself and resume the dive. So for God's sake, stay calm and don't fight the downcurrent. Swim to the sides till you're out of it."

Are You Experienced?

Unless you are properly trained, physically fit, and intentionally seeking out the challenges of strong vertical currents, it is best to avoid areas where they are known to be fierce. But unfortunately, many dive operators take novice divers on dives out of their depth. H. Wayne Ferguson (Lawrenceburg, IN) experienced this while diving the Galapagos Islands. "On one of the early dives, we hopped in the water and went from 10 feet to 50 feet in nothing flat. The woman who was my dive buddy became very excited and grabbed hold of me, with a wide-eyed look of panic on her face. I checked her equipment, verified that she was OK and had sufficient air, and we slowly made our way upward. There were a number of divers on this boat who had a limited number of dives and were lacking experience in a place which could cause problems." One must wonder what novice divers are doing booking the Galapagos, anyhow.

"One diver panicked and came up with a
computer beeping and flashing red lights.
Another diver claimed to be okay, but
suffered a panic attack an hour later."

Mary Wicksten (Bryan, TX) saw the detritus of novice divers caught in a downcurrent at Palau's Blue Corner. "The current was so strong, it almost pulled my regulator out of my mouth. My group was scattered all over the top of the reef, hanging on for dear life and to hell with the coral. I signaled to the dive guide and surfaced. The chase boat got me quickly, but the driver chewed me out for coming up alone. I agreed I was an idiot, and happily breathed fresh air. Then another guy came up, alone. He was in the downcurrent that swept the group to 80 feet plus, like an elevator out of control. He 'mountain climbed' the reef and came up with barely 100 psi. The next guy swam out to sea and got away from the current -- a long, long way from the reef in openwater. Other divers came up here and there, but at least one other diver panicked, pulled her carbon dioxide cartridge and came up with a computer beeping and flashing red lights. She was taken to the chamber in Koror. Another diver claimed to be okay, but suffered a panic attack on the boat an hour later. Mine was a very mixed group, but I strongly suspect that at least two of the divers were absolutely clueless as to what, if anything, they could do. Dive boats away from the U.S. will take just about anybody on 'adventure' dives."

Of course you expect your divemasters and guides should to be aware of problem sites, and at least advise divers about them. Stephanie Runyan (Brooks, GA) was fortunate to get a lesson from her Utila divemaster. "Before we selected the dive site, she asked our group of five divers if we had ever experienced a downcurrent situation. Only two had. She provided specific instructions, telling us that on the forward part and sides of the reef, we could stay off the mount a few feet but get close to the reef again on the downcurrent side. To get out of the current, we should swim to the side (similar to a rip current), then come up the reef if there are enough divots and overhangs. She wanted us to experience the power of the downcurrent."

Even vertical currents aren't always predictable. There may be surface manifestations, like circumscribed areas of water showing varying patterns of wave frequency, height and direction interspersed with eerie, mirror-smooth areas, but don't count on this.

Often surface conditions tell the diver nothing about currents at depth. If caught in a vertical current, one strategy is to swim out from the wall immediately, drop off or any other apparent source of the current. Vigorously fin away, but do not exhaust yourself. It's helpful to orient yourself to bubbles or the direction and angle of any fish you observe. If you're caught in an upcurrent, swim away and down. For a downcurrent, swim away and upwards.

Monitor Depth, Keep a Hand on the Deflator Valve

It's best if you can make adequate upward progress without BC inflation, as an inflated BC provides more surface area for the current to push against, and raises the risk of a poorly-controlled ascent once you are released. However, you may need to inflate if rapidly descending or lacking adequate gas to ride out a downwelling that does not show rapid signs. Marc Fountain (Berkeley, CA) says he always tries to resist the urge to inflate his BC a lot in response to a throwdown. "Inflate it just a tiny bit to help stabilization, and try to swim up slowly. But be prepared for the next reverse cycle -- the coming throw upward from 150 to 50 feet that will leave you scrambling to deflate quickly if you have too much buoyancy."

PADI instructor Bob DeFeo (Novato, CA) says divers should be cautious when swimming laterally out of an up or down current. "You may run into a current going the opposite direction right next to the one you're getting out of. Keep your hands on the inflator and dump valves, and be cognizant of your body position in the water to make effective use of them."

Do monitor depth and keep a hand on the deflator valve, as you must avoid shooting to the surface when the current relents. Consequently, it is also best not to release your weights if possible, but in very serious situations when there is no other way up, it may be necessary. In any vertical current, remember to breathe normally. While caught in a downcurrent in Sipadan, Owen Babcock (Denver, CO) says his quick, automatic response was to "stop, inflate the BC and begin kicking upward with great vigor. Holding the inflator valve button in one hand and depth gauge in the other, I was out of the downcurrent in about a minute. I actually had to dump a small amount of air in about 10 seconds, then fairly steadily for an additional 30 seconds. The moral: Keep a better view of surrounding objects and check your gauges more often. A downcurrent happens incredibly quickly and without any feeling of rapid descent."

An alternate strategy if you're near something graspable is to kick to it, grab on and pull yourself in the desired direction until you are free. (We get reports of autocratic divemasters grounding divers for grabbing coral in stiff currents -- don't let them intimidate you.)

Whichever method you employ, use surge to your advantage. When it propels you in the desired direction, go with it; conserve your energy when it is working against you. While sudden vertical currents are anxiety-provoking, you can frequently negotiate them. As in other stressful scuba situations, remain calm and take rational problem-solving action.

When in doubt, don't do it, says Randy Preissig. "Know your limits. Although still 'in shape,' I'm older, and I actually aborted a strong current dive in Australia when I weighed the 'risk-to- benefit' ratio." If you do decide to do it, he says, "Don't let the excitement of the minute or the newness of the experience take your mind off your routine -- that's when you need discipline the most."

A Popular Place for Downcurrents

A final note: Cozumel is notorious for its vertical currents, and nearly every dive is a drift dive. Especially in the early and middle parts of Caribbean hurricane season, it's not unusual for divers to face heavy downwellings and roller-coaster-like horizontal currents. Reader Jeffrey Raffa (Boca Raton, FL) went there last June to dive with Dressel Divers, but gave up. "The currents were just too strong. This was my fifth time there, but on this trip, they were out of control."

On YouTube, "AquariumDiver" uploaded his video ( www.youtube.com/watch?v=y39SQg26z2M ) of "the most intense dive of my life" while 75 feet deep at Palancar Gardens last June. He writes, "It was even worse a few moments before -- a whiteout, then it started to get dark, and the currents were whipping us back and forth ... hanging on with both hands to not be swept away! At that point, I wondered if it was a tsunami. Only after it started to calm down a bit was when I shot this video. Divemaster said it was the most intense current change he ever saw."

While the diving there is exciting, it can often be intimidating for beginners or those who lack confidence in their skills., and the results can be fatal. Christina Cassin from Acworth, GA, vanished while diving Cozumel's Santa Rosa Wall this past March. Cassin, 49, had made approximately 10 dives after getting her openwater certification. She was on an 11-day cruise with her husband, Scott Turco, and they decided after docking in Cozumel to do some diving, but the current was so strong that day that tank bubbles were apparently pulled to the ocean bottom. Turco told news station WSBTV that during their dive he "turned to let the divemaster know we were going up, and when I turned back, I didn't see her." He feared she was sucked beneath a reef and didn't survive. The Mexican Navy and Coast Guard led a land and sea search, but called it off after 72 hours with no sighting of the grandmother of four.

- - Ben Davison and Vanessa Richardson

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