Part I: The Ups and Downs of Ocean Currents

One can dive his entire life and never find much in the way of currents. But every so often, a combo of tides, wind and other factors can create currents that can throw you a surprise.

For example, Nick Macelletti (Sarasota, FL) was calmly finning along at Delila Reef in Cozumel when an unexpected current sent him unwillingly to the surface. Reunited with his group on board, he learned they all had been separated like pins hit by a bowling ball, although no one else was brought to the surface as he was.

The more you dive in sites affected by big ocean tides, the more chances you'll have of experiencing a topsy-turvy dive, as our readers attest to below. Sometimes, it's only a mild shake-up that adds a little zing to a mild Caribbean dive, as Macelletti had. But sometimes, you'll have to keep your cool and remember what's needed to get out of an upor down-flowing current safely.

Thrown into the Washing Machine

When an ocean current meets an immovable object such as an island or a submerged reef wall, it has to divert around it, and, rather like air passing over the wing of an airplane, it has to speed up to do so. The problem for divers is that the current can go left or right, sometimes over the top of the obstruction, or sometimes downward to form an eddy at depth. It's these upward and downward currents that cause a problem for divers, especially if you encounter one near the end of a dive. Nobody can swim against a current that flows at more than one knot for more than a short time, and some of these currents are faster.

One initial sign of a downcurrent is when you put up a surface marker buoy that ascends in a satisfying manner, only to find it changing direction and coming back downward still fully inflated. At that time, you'll find yourself enveloped by your own exhaled bubbles, and you might even find yourself hurtling along helter-skelter and rotating uncomfortably out of control. These dive sites are often called 'washing machines.'

Harvey S. Cohen (Middletown, NJ) wrote us about a dive in the Bahamas near Highbourne Cay Marina, known as "The Washing Machine," where the tide rushes through a gap between two islands, creating a vortex along one of the wall edges. "The diver is pulled horizontally by a fast current while rotated up and down through one or two complete circles. It's fun!"

"You are literally tumbling along through the area -- upside down, sideways, inverted," Michael Ring (Santa Barbara, CA) writes of the same dive site. "And you are really moving. Fast! The exhilaration level is quite high, as you find yourself being carried along at seemingly incredible speed, sometimes what appears to be directly at the rocks, with no hope of avoiding impact. Then the current will swirl you clear of catastrophe, only to do it all again in the next few seconds."

Notable Dive Sites with Downcurrents

A great reason to enjoy diving in currents is because marine life loves them. Visit Blue Corner in Palau during a slack interval between tides, and you'll wonder why it is rated so highly. But go again when the current is running at several knots and it's a different story, as you'll see plenty of sharks and other large pelagic life surfing effortlessly in the flow.

Mick Domagala (Chicago, IL) confirms this, but he had a scary experience when he was quickly taken by a current down to 130 feet. "We must have made our way out on the ledge far enough to hit the brunt of the current, or it just kicked in stronger at that point. Whatever it was, we didn't need to be in the middle of it." He enjoyed the dive, but he wishes he'd been alerted to this possible deadly phenomenon during the dive briefing. It's good to remember that any wall has the possibility to send water -- and divers -- downward with a strong force.

John Yavorsky (Warren, IN) experienced an unusual current at the southern edge of Turneffe Island in Belize. "A cold surface current was falling down the edge of the underwater wall. Our bubbles flowed down, and we had to use BCs to buoy us up against the current until, at 30 feet, we had to expel that air to get negative and crawl along the sand channel back to the boat. By digging a knife into the sand, I could anchor and then sprint 10 feet against the current and anchor again. Fortunately, everyone figured this out and got back to the boat. We called it the 'Niagara Falls Dive'."

You can shelter from an unwelcome current by hiding behind rock or reef formations, just as you might take shelter from the wind. Alan Riggs (Denver, CO) and his friends would do this when diving Deception Pass in Washington's Puget Sound. As experience got them used to the abrupt velocity shears and passing turbulence boils, they were able to dive closer to the corner of Whidbey Island, where the current was strongest, ducking into depressions in the island wall to watch things rush by in the current. "After that, resort diving could be pretty dull."

Asia-Pacific's Shifting, Seasonal Currents

People are often surprised when they first dive in places in the Maldives or the Indonesian archipelago, not by the strength of the current but by the vagaries of its direction. Situated as they are in the middle of the Indian Ocean, the Maldives' currents tend to be seasonal, but where an archipelago such as the Indonesian islands separate the tides of major oceans from smaller seas, they stay the same throughout the year.

For example, at Cape Kri, the classic dive in Raja Ampat, there is usually a strong current that takes you in a comfortable drift along the reef wall 60 feet deep, only to suddenly whisk you down to 130 feet just as you are thinking about ascending to safety-stop depth. Of course, it soon brings you up again, but not before it has made you soil your wetsuit the first time you do that dive.

Sardines and Mike's Point are similarly difficult dives in Raja Ampat. Finding himself in such a washing machine while diving there, Fred Turoff (Philadelphia, PA) reckons it was one of the toughest dives he has ever done -- he was yanked down to 88 feet and aborted the dive after only 13 minutes underwater. Of course, if you can manage such conditions, these currents attract the highvoltage marine life the area is famous for.

Mel McCombie (New Haven, CT) loved diving around Siladen/Bunaken in North Sulawesi. "Whenever we noticed our bubbles spinning into the water like soda bubbles and hanging there, it was time to hug the wall. We could feel a downward tug and sometimes saw our bubbles not only sit suspended in mid-water but also spin downward. On one dive off Bunaken, the down current was so powerful, we were forced to 'gecko dive' -- cling to the wall and pull ourselves across it by hand -- or face a quick trip to the bottom of the ocean! Usually a down current could be handled by just staying close to the wall, where its contours would break up the current, but sometimes the only way to not be carried off was to cling to the wall."

David Hill (Gloucester, MA) had a similar experience in the Philippines. He ended up clinging to a wall with his buddy after their dive group encountered a current that swept both upwards and downward. It was bizarre to see his buddy's exhaled bubbles go straight down. Then he was swept one way, while the dive guide was swept the other. One of his group was sucked down to 80 feet and rushed back up to 20 feet several times in succession.

Sucked into an Underwater Whirlpool

Bruce Yates (Bellevue, WA) has a harrowing story about Indonesia's erratic current effects when he was diving near Komodo and Rinca Islands, where the waters are known to have ripping currents and sizable "washing machine" whirlpools. He says, "Some years ago, on a liveaboard trip there, we dove a site called Current City, a small, unassuming seamount where the surface current didn't seem bad at all. We dropped in on the lee side and were told in the briefing, 'If the current is too strong, just go a little deeper and it should be less.'"

"As soon as we descended, the current was actually blasting along, and it was all we could do to hold onto dead sections of the reef to avoid getting blown into the blue. My buddy had little trouble because he didn't have a camera, but my big rig acted as a sail, and I struggled just to hold on, let alone attempt photos. At about 30 feet, with several other divers nearby, I signaled him to stay put and that I was going a little deeper, assuming that the briefing was right, and the current would be less down there. By the time I got down to about 60 feet, however, the current was every bit as strong, so I decided to abort the dive. I let go to do my ascent and safety stop in the blue, knowing the crew was assiduously tracking our bubbles. I had over 1000 psi of air and expected an uneventful drift and safety stop."

"While on my safety stop, I suddenly noticed the water was more turbulent, my bubbles were swirling around and going down instead of up - and so was I. After drifting 50 yards from the seamount, I had been pulled into a big whirlpool. My dive computer's depth gauge went berserk, jumping around from 20 feet to 60 feet a second later, then 40, 30, 50, and so on. Whirlpools can create false depth readings because the increased pressure of swirling water is interpreted by the computer as a greater depth. The only thing I knew was that I was definitely going deeper, no matter how hard I kicked toward the surface, which was my natural impulse. More concerning, I was rapidly depleting my remaining air between the exertion of kicking and rapid breathing."

"I began swimming as hard as I could horizontally to get out of the whirlpool, just as you swim parallel to a beach to get out of a riptide. Sure enough, within a minute or two, I was back in calm water, albeit still at roughly 40 feet. I began another ascent and, at 20 feet, began a short safety stop because my air was low."

"Before I knew it, I was back in the whirlpool, but this time I had almost no air left, and I soon felt the telltale tightness that signifies the tank was near empty. Knowing I had only two to three tight breaths left, I made a decision: I could either breathe that air, which I knew would not get me to the surface, or inflate my BCD and see if that would."

Had Yates done the former, he wouldn't be here to share his tale. But with that last breath, he simultaneously inflated his BCD with what air was left and started swimming horizontally. "Essentially, I was doing an emergency swimming ascent, but letting the BCD handle the ascent part. With no time for another safety stop, I let the BCD's buoyancy take me toward the surface, while I quickly switch let air out as I exited the whirlpool to avoid rocketing to the surface."

Don't Panic; Just Be Prepared

So what do you if you get caught in a downcurrent? As Yates said, your first inclination is to fin strongly upward or fully inflate your BC, but that's often ineffective. The second inclination is to grab the reef wall and do a bit of rock climbing.

You don't have to do either. A downcurrent is like an underwater waterfall; it's very localized. The astute diver swims horizontally and preferably away from the underwater topography that's causing the phenomenon, to get out of the flow.

And during the briefing, pay attention to the name of the dive sites -- if any have "Express" as part of their names, prepare yourself for a bumpy ride. Kuredo Express in the Maldives is a notable one that comes to mind. Constricted by the islands and submerged reefs and diverted up and down by the topography of the seabed in the channels, the ocean flow speeds up there to give divers a wild ride. Divers expecting leisurely conditions can suffer a scary experience if they don't know what to do.

However, don't be put off visiting these places. The mindful diver has nothing to fear. I'm in my 70s and not that powerfully built, but I've dived virtually all of these abovementioned sites and enjoyed myself while doing so. It's high-voltage diving.

Panicking won't do anything; being prepared for some literal ups and downs when they happen will keep you from injury. And it will certainly be a notable dive you'll remember in detail, tell your buddies, and hopefully share with us.

-- John Bantin

Next month: Readers share their experiences in strong horizontal currents; and what to do when you surface a long way from your boat.