Thresher Sharks on a Dangerous Day

The following morning we dragged ourselves out of bed at the ungodly hour of 4 AM for our Deep Dive with the stars of the show, thresher sharks! This dive would take us to 30 meters and make us qualified to go that deep again in the future. Since I was small I have been fascinated by sharks and still have a lot of books about them so needless to say I was incredibly excited. To make things even more exciting a stiff breeze had kicked up during the night and the ocean was rolling. We motored out into the darkness in a small boat and then had to jump from that one onto a bigger banka boat in the fast moving swells which was a bit of a stumbly affair. It was a very bumpy and somewhat nervous ride of about 40 minutes as the wooden boat pitched in the swells, the outriggers slamming down with a shudder into the sea every few seconds. Almost everyone on board was soaked from the splashing water after just a few minutes. About half way to the dive site, called Monad Shoal, the sun finally came up. I’m not sure if it made the trip any more enjoyable or not, as we could now see all the white caps and how rough the sea actually was.

Getting off the boat was a bit tricky. With the ocean in that state it was difficult just to stand, never mind waddle up to the bow with flippers, a heavy air cylinder, and do a safe long stride entry into the water. Emily managed it alright and swam quickly to join Dan at the mooring line away from the dangerously pitching boat. If you didn’t get away from the main body of the boat and its long outriggers they could easily smash down on your head and kill you. When it was my turn I forgot to hold onto my mask and weight belt as I half stepped/half fell off the boat and swam to join the others. I realized the buckle on my weight belt had popped open, but luckily I was able to grab and re-secure it before it fell off and sank to the bottom. We let the air out of our vests and descended, clawing our way down the mooring line. Just several meters below the surface the chaotic surging water calmed down and I was able to catch my breath and start enjoying the dive, pushing the thought of trying to scramble back on to the boat to the back of my mind for the moment.

We were told they see the sharks about 90% of the time but the day before they hadn’t seen any. Hoping the same misfortune wouldn’t befall us, I was absolutely thrilled when Dan pointed up to the right after just a couple of minutes on the bottom. The unmistakable shadowy silhouette of a thresher shark appeared out of the blue, swam by, and disappeared again just as quickly. I couldn’t help but smile so big that my dive mask filled up with water and I had to empty it. I was so excited I can’t even remember on how many occasions we saw the sharks. It seemed like every few minutes one would emerge from the blue somewhere within our 20 meter field of view and then disappear again. Thresher sharks are pretty well harmless to people and are very distinctive looking, with a very long, slightly curved tail resembling the threshers used to harvest crops before the industrial revolution. While hunting they whip them through the water to stun fish, which are then much easier to catch and eat.

Emily and I followed Dan down to 30 meters where he pulled a packet of instant coffee and a rubber sandal out of his vest to illustrate to us the effects of water pressure at that depth. The coffee packet looked as though it had been vacuum sealed. The rubber sandal was misshapen and compressed to several sizes smaller than it was on the surface. It’s remarkable the body can withstand that amount of pressure with no major issues as long as you equalize your ears and follow the other rules of diving. Like everything else at that depth the air  breathed out of the cylinder is compressed and as a result you use about twice as much as you do at 10 meters, meaning you must check your gauges twice as frequently. The air we breathe consists of about 70% nitrogen, while the remainder is made up of oxygen and trace amounts of other gases. Much higher concentrations of these gases dissolve into your blood under that amount of pressure especially the main ingredient, nitrogen.

This means it becomes more important to make sure you do a 3 minute safety stop at 5 meters on the way up to give your body a chance to remove it from your circulatory system. If you don’t the partial pressure of nitrogen in your blood could exceed that in the atmosphere and the equalization process could be biologically disastrous. After ascending too rapidly this manifests itself as the deadly decompression sickness, or “the bends” where the nitrogen can bubble out of the blood suddenly, causing a stroke or an assortment of other maladies. Interestingly, that isn’t the only nitrogen related risk of diving. The other is called nitrogen narcosis, which typically doesn’t set in until depths well below 30 meters, but it has been known to happen in shallower areas to those sensitive to the affliction. The result is not harmful except in that it basically involves becoming inebriated suddenly underwater. Those who have had it describe a feeling of euphoria, but it also leads to stupid decisions and skewed thinking that could get you killed, similar to driving while drunk.

After the coffee packet and rubber shoe show we swam up to a little plateau where the rest of the divers were waiting for sharks to show up. The dive operators had anchored horizontally tied ropes to the bottom that you could hold on to and look out over a drop-off into the blue ocean. We hung out there for a few minutes and saw one of the most amazing things I’ve ever witnessed in my entire life. One of the sharks swam up to us right at eye level and circled directly in front for a minute or two, coming within 6 or 7 meters of us. You could see every detail of it, from the large whites of the eyes to the curving lateral lines stretching the length of the body to the shape of the strangely positioned mouth on the bottom of its head. It was truly something to cross off the bucket list and especially incredible because just a couple of weeks beforehand we had been learning how to dive for the first time. With renewed confidence from the encounter we ascended, did our safety stop and clambered back onto the boat without as much trouble as I thought it was going to be.

We had three dives scheduled that day; the second would be a Fish ID dive off the west side of the island. We had to spot 5 fish underwater, draw them as best as we could on Dan’s underwater paper and then ID them back on shore. At the relatively calm dive sites around Nusa Lembongan, Indonesia where we did our first dives this would have been a fairly easy and straightforward assignment in crystal clear water. Instead it turned into a difficult exercise that almost went very wrong. Stephen later told us he has done over 60 dives all over the world and never saw a dive company disregard common sense safety measures like this one did.

The wind was coming out of the north so as soon as we came around the west side of the island we were in the thick of it. It had picked up since the early morning dive and the waves must have been almost twice the size as they were then. The banka boat shuddered and shook as it got tossed around and people stumbled around banging into things on board while trying to get geared up. It was chaos trying to get in the water. Dan jumped in first and started yelling that the current was incredibly strong. He had to swim very hard against it to reach the mooring line. With that in mind Stephen jumped in next and made it to Dan without too much trouble. Just as Emily was about to move to jump off the bow the captain yelled at us not to hold the mooring line because the boat was tied to it and with the big swells it was getting ripped up and down through the water column with the full weight of the pitching boat yanking on it. Dan had told us to grab it as soon as we were in the water so we weren’t sure what to do and it was impossible to hear anyone clearly with the sounds of the crashing waves.

Em stepped off and swam quite well towards Dan and Steve. I wasn’t long after but I hadn’t had a chance to put my flippers on yet. One of the local guys on board started yelling to get them on immediately. He ran over and shoved them on my feet and yelled for me to jump in as they were holding the boat there under power to ensure it was close to the mooring line. Confused, I jumped in and started swimming as fast as I could toward the others, all the while with waves washing over my head and having to breathe from the regulator instead of the snorkel. I raised my head out of the water to hear Dan and Stephen screaming at the top of their lungs at Emily telling her to swim. She had quit kicking to clean her mask and instantly the current had taken her straight toward the boat. When I saw her she was only a meter or two from the massive bow as it rose up and plunged back into the sea so close to her head I thought for sure things were all over. I’ve never been so scared in my entire life and started yelling at her to swim.

One of the local guys on board jumped into action and threw her the floating ring. She grabbed it just in time and he pulled her out front of the bow, out of harm’s way but just barely. From there she was able to make it to Dan and grab the mooring line. At the same time all this was happening the release on my flipper popped off because it hadn’t been fastened properly. Suddenly I was without propulsion on one side and started drifting in the current toward the outrigger while struggling to get the fin back on in the rolling sea. The outrigger too was rising several meters out of the water and smashing back into the sea just a couple meters from me when the floating ring was tossed my way. They pulled me to the front of the bow, Dan helped me get the flipper back on and we all pulled ourselves underwater on the mooring line.

The visibility was terrible, the current was the strongest I’ve ever been in, and I think both Emily and I were hyperventilating. When we finally got to the bottom we all followed Dan to the shelter of an underwater wall where things were quite calm and we could regain our composure. Then he handed us his tablet and the underwater paper so we could draw our 5 fish. All three of us managed to get 5 fishy images scribbled down on the paper just in time to make the ascent. At the 3 minute safety stop I looked at my air and saw the gauge only read 20 bar. That’s quite low seeing as how you begin a dive with 200 bar, always start ascending when you get to 50, and should never have less than 30, so I was eyeing up Emily’s spare regulator just in case I ran out at the last minute. While we were doing the safety stop, clinging to the mooring line, it felt like we were flags flapping in the wind. The current was flowing with such force we were all stretched out lengthwise parallel to it getting jerked up and down and back and forth with the surge. After 3 minutes in that position we surfaced into the same chaotic scene we had left less than half an hour before.

We followed Dan under the support for the outrigger and clung on to the ropes hanging from it. Em went up the ladder first and I went second, finally breathing a sigh of relief. When I told her I only had 20 bar left and that I was thinking about grabbing her spare regulator if need be she told me she had only 10 bar left! Stephen, who is much more experienced than us later emphasized that in all his years diving he’s never seen such a close call with the boat nearly hitting someone. Emily hadn’t realized how dangerous the situation was until we were all talking about it afterwards. A real Miss. Magoo moment if you ask me. We were pretty beat from the early morning and all the excitement so decided not to do the third dive of the day. Instead we would join Stephen the following morning and go back to Monad Shoal to see the sharks again. That evening we had a great time with Stephen, Catherine, and one of the other dive instructors at the dive resort bar.


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