Life In The Fast Lane
The lagoon at Aldabra is the size of Manhattan Island and it fills and empties with each tide through three narrow channels that provide the scuba ride of your life.
Twice a day, the water empties out of the Aldabra lagoon with the falling tide into the Indian Ocean and then refills with the incoming tide. It also washes out all the fishes that browse for their food within it. As the tide turns, the fishes congregate at the mouths of the three channels that feed the lagoon. They wait to get back in. There is Main channel, East channel and Johnny channel.
The inflatable boat drops divers in the ocean outside Main channel. A couple of female passengers from the diving liveaboard Indian Ocean Explorer, wish to do it by snorkelling at the surface. The sea has a huge swell and it’s good to exchange the discomfort of a bouncing dinghy for the weightlessness of the deep. Thousands of fishes hover in silent aggregation but their relaxed appearance belies a current that is already moving at more than one knot.
The divers cling to the rocks. They are envious of the one with the reef hook that allows him a hands-free approach. Another diver hangs on to him. He is impressed that his hook and buoyancy control is strong enough for both of them. Then they decide they have waited long enough and let themselves go with the flow.
Main channel is about 30 m (100 ft) deep in the middle. It is several hundred metres wide. The underwater visibility drops to around 10 m (32 ft) and one diver soon loses sight of the others. He bowls along with the landscape rolling below him. He finds it hard to maintain one depth. He tries to keep at 22 m (70 ft) but one moment he is deeper and the next he is racing near to the surface. The currents have an up and down aspect to them too it seems.
Giant groupers and huge potato cod rush out from hiding to inspect him as he passes. They are waiting in ambush for smaller prey than he. Massive bumphead parrotfish veer away out of sight. Every rocky arch he passes seems to be hiding some underwater warrior ready to gobble up the unwary. It’s like a giant computer game and he is in it.
Forty minutes pass. Our solo diver begins to wonder where the others are. He works out that the closer to the stationary underwater surfaces of the island you travel, the slower you go. He heads out into deeper water to put on a bit of speed for five minutes and then heads back.
Miracle upon miracle, he joins the main group. “Where have you just come from?” is written all over their faces. They can’t wait for the next rising tide to do it all again.
They wait until next day before they go in again with the inward flow. It would be rather silly to do it with the outward flow. Who knows where you would end up? The solo diver heads off on his own again. This time he goes for the left-hand side of the channel. Everyone else seems to opt for the right. It’s another fast ride a bit like a Star Wars X-wing ride. When he surfaces he has left the turbulent water of the ocean behind and is in a tranquil, flat, turquoise sea. About half a mile in one direction he makes out a small cluster of figures around a safety sausage. He can see another safety sausage a mile behind him. He erects his surface marker flag.
But there is no diver pick-up boat in sight. Only the Indian Ocean Explorer is visible at anchor in the ocean beyond the channel, and still coasting on a fast current, he soon loses sight of that behind the low coral islands that rise above the walls of the lagoon. Remembering that the water flows more quickly where it is deep, he uses his flag as a sail to send him out into the middle. The furthest group appear to be swimming towards him but they are not. They, like him, are still travelling into the lagoon but he is travelling faster. He uses his flag to vector his course back to them. They are amazed at his newly found sailing skills. Quite frankly, so is he.
David Rowat, the captain of Indian Ocean Explorer, is in this group. He’s suffering a sense of humour failure. Where is the pick-up boat? They are in the confines of a lagoon. It may be as big as Manhattan but there are no tall buildings to become obscured by. They know it is just a question of waiting. The only hazard seems to be getting torn on fire coral as they rattle past it.
Eventually the inflatable pick-up boat arrives. They have been waiting 30 minutes. The snorkellers had blown the plan and decided to stay outside the channel in the ocean. The boat crew had wisely opted to stay with them and pick them up first. One reports that the yellow surface-marker flag is far more visible than the orange safety sausages. Rowat makes a mental note to order a number for the boat so that all the future passengers can have them.
Next day they decide to up the voltage somewhat. They dive East channel. It is much narrower. At 22m(65 ft) to the bottom you can still see both sides. It’s a narrow gorge. The water is moving like a torrent.
Two divers hurtle along together, following the bottom. Another guest diver and the captain are just ahead. There are shifting banks of sand that act like speed bumps. You never know what’s on the other side. They make a mental note to avoid impacting with stingrays that might be browsing there. No rays are evident, but in quick succession they each have a close encounter with a large nurse shark. A giant grouper hurtles out and checks his make-up in the reflective glass dome port of an underwater camera, before ducking back under the cover of a rock. Ahead they see Rowat, dragged by his surface marker buoy on its line, lift his legs to let a bull shark hurtle under. Everyone goes up.
They are doing around ten knots and the bull shark is doing at least the same against the flow. That’s a closing speed of 20 knots. The photos taken are not perfectly sharp but then what would you expect?
Seventeen minutes into the dive they are back in shallow water. They surface and see the pick-up boat waiting. It’s a rush to get every bit of kit into it as they pass. The boat has a strong wind behind, opposing the flow of the water. The divers climb in ecstatic. Captain Rowat tells them that there were in fact two bull sharks, coupled in love until he almost crashed into them. One came out and the other went into the lagoon, both in panic.
“Let’s do it again,” suggests one diver.
This time cameras are left behind in the boat. The current is even faster. They belt through the channel, passing another nurse shark, but it seems they’ve already startled the major part of the wildlife. It’s all over in only 11 minutes.
The boat is right there. Getting back in the boat is done more slickly this time. They know what to expect and take their aqualung sets off before they get there. It’s up and over the inflatable tubes while the crew pull in their tanks. “You came too quickly!” exclaims one overexcited woman diver to the boatman.
Then there is Johnny channel. This is the really fast one – probably 15 knots. They motor slowly through it against the flow in the inflatable. It twists and turns among the mangroves. No one is rushed to get in the water. It’s not for the faint-hearted. If you like to dive with pretty fish in swimming pool conditions, don’t bother to apply!
© Not to be reproduced without written permission from Fernhurst Books Limited.
Amazing Diving Stories is written by John Bantin. John Bantin learned to dive in 1979 and in 1992 it became his career. He was technical editor for Diver Magazine, Britain's most popular diving magazine. During the past 20 years he has travelled the world gaining many different experiences underwater (not all of them good) which has furnished him with a vast store of anecdotes. He is now known as something of an accomplished raconteur in the diving industry.