Sharks rarely attack divers, he reminded himself. Or only sharks like White Pointers and they are creatures of the cold Southern Ocean and are rare in tropical waters. But the intellectual theory was small comfort to his worries.
Ella began swimming southwards with the reef ten metres to her right. Andrew set off parallel a few metres further in. He saw that Carmen and Tristan were already ten metres ahead and fifty metres out to his left front. They were going deeper and were doing a survey of the seagrass on the seabed. There wasn’t much visible and Andrew did not think they would see much.
Not on the seaward side of the reef where the big waves work, he thought.
Checking the distribution and health of the seagrass was part of Tristan’s thesis study and so far they had found little, only a few isolated pockets in the shallower, more sheltered water on the western side of the reefs. Andrew and Ella had the task of surveying the number and size of the brain corals on the edge of the reef. They also had the secondary task of helping Dan calculate the amount of seaweed that was growing on the actual reef. That was the topic he was researching as there was some evidence that the seaweed was encroaching on the coral. To do this Ella had an underwater camera and both had small plastic slates and crayon pens. At present the water was too shallow to swim safely across the top of the reef without risking injury to themselves or damage to the coral. They would do that from the boat during the high tide period.
Drawn on his plastic slate Andrew had an outline map of the reef overlain on a grid which showed every ten metres to scale. Using the pen, he began to mark on brain corals and seaweed as he saw them, using dots for brain coral and small squiggly strokes for the seaweed. The work at least took his mind partly off his fears. He swam just below and to the right of Ella so she could take photos every few metres. The distance swum they had to estimate.
All the usual small fish flitted among the coral, but Andrew had seen too many sunfish, clown fish and other colourful types to be really interested. Instead he kept glancing around to check that nothing large was eyeing him off as a potential meal. The day before a large shark had cruised by and just that one fleeting glimpse had reignited all of Andrew’s fears.
The only really good thing was that the visibility was excellent. Usually it was about fifty metres, but he estimated he could see clearly almost twice that.
Probably because we are so far from the mainland and there has been no strong wind for a week so the waves haven’t stirred up the silt, he thought.
The sandy seabed was only about twenty metres below, with Andrew swimming at ten metres and Ella just above that. Carmen and Tristan appeared to be swimming along about five metres above the sand.
This isn’t too bad, Andrew decided.
In an attempt to overcome his anxieties, he refocused on his job and made a point of trying to note all the different types of fish that he saw. Knowing that tourists paid big money to do exactly what he was now doing added a distinctive twist to his sense of the absurd.
After about two hundred metres Andrew noted that the wall of the reef was trending in to a sort of a bay. He had been expecting that because the air photos of the reef showed just such a shape. The increased current flowing into the ‘bay’ was also expected because they had found an obvious gap, like a miniature canyon, extending deep into the reef when they had surveyed the other side earlier in the morning. The old survey charts did not show any channel or gap but the air photos did and Andrew agreed with the suggestion that there was probably a narrow pass right through the reef.
So he swam into the narrowing gap behind Ella, noting that the current was increasing every second. The tide was now on the rise and was squeezing through all the gaps in the reef as the ocean level rose out to the east. We need to be careful here, he told himself. So he swam up beside Ella and got her attention. Using gestures, he shook his head and swept his hands across to indicate ‘no’.
She looked at him quizzically, so he turned his slate over and printed the word ‘current’ and held it up for her to read. She looked, then nodded and gave a thumbs-up. By then they were right in the mouth of an obvious passage. It was about ten metres wide and the same deep with vertical sides and a sandy bottom.
Both now turned and began swimming back against the current. This turned out to be much harder than Andrew had expected and he quickly revised the current speed from three knots to five or six.
Anyway, enough to make this hard work, he thought as he finned hard against the flow. The effort soon had him sucking in big lung-fulls of air and he knew that wasn’t good.
Need to take it easy, he reminded himself.
As they swam back out into the wider ‘bay’ area the current eased and they were able to make more progress. Ella stopped to take another couple of photos and Andrew made more notes on his slate. Then they resumed swimming south along the outer edge of the reef. As they did Andrew looked around for Carman and saw her and Tristan in the distance. They were now on the limit of visibility and showed only as flickering shadows.
We had better catch up, Andrew thought.
He began powering after them and then flinched with fright when Ella touched his arm. He looked at her anxiously, but she just smiled and pointed to her pressure gauge. That made Andrew feel guilty as they had been down for fifteen minutes and he knew he should have remembered to check hers every ten. So he slowed while she looked at his gauge and then gave him the pressure reading by hand signals. 175psi she informed him. That was plenty for the twenty or thirty minutes they might still be down at such a shallow depth. Andrew checked hers and saw that it was 180psi and the thought that she was a more skilled diver irked him a little.
Both then resumed their survey, swimming slowly along the side of the reef. By then they were well away from the Challenger Channel and the inky blackness no longer threatened. Instead the visibility just shaded off through pale green to a dark greeny-yellow and then to a sort of shadowy darkness. The only larger creatures Andrew saw during the next five minutes were a couple of stingrays which kicked up sand as they moved or tried to hide. There was not even a large parrot fish or groper visible.
Then a flicker of movement up to his right front sent a shiver of fear though Andrew. He looked anxiously up and then breathed a sigh of relief. It was a large turtle. The creature had swum into view over the top of the reef and now dived across their front and swam rapidly off into the gloom. Andrew watched it with admiration. Turtles were reptiles that he really liked.
Green turtle or a Loggerhead? he wondered, staring hard to try to pick out the salient features as it swam almost directly away from him. Green, he decided.
Two minutes later, another flicker of movement out to his left resolved itself not into a friendly turtle but into what he had feared—a large shark! It had come from behind and was swimming slowly along in the same direction and he was sure it had seen them.
Andrew felt his heart skip a beat and he began to breathe rapidly. Reaching out he tapped Ella and pointed to draw her attention to the thing. It looked to be a bronze whaler and Andrew estimated it to be four metres long.
Big enough to chew me up anyway, he decided.
Ella looked and then nodded and even took a photo. Andrew watched with his stomach churning and his whole body cringing as the shark swam up level with them about twenty-five metres away. He tensed, ready to try to fend it off and then he fingered the handle of his sheath knife with his right hand. Then he realized that he was seeing dots and that his vision was going blurry.
I am hyperventilating, he told himself. With a conscious effort of willpower, he slowed his breathing.
For a moment the shark turned towards them and Andrew glimpsed the rows of vicious looking teeth and his blood ran cold.
It is going to attack! he thought. He gripped the knife, ready to draw it.
But it didn’t. Instead the shark turned away and swam off to the left front out into deeper water. As it went Andrew sighed with relief and, despite his fear, was able to admire