Despite their dinosaur-like dimensions and mouths wider than my bathtub, whale sharks are relatively harmless creatures. Image Credit: Getty Images

The French woman on the boat seems to be shouting at me to get out of the way in what could be the kind of overripe language Parisian taxi-drivers use for myopic foreign pedestrians trying to cross the Champs-Élysées.

I’m treading water about 100 metres off the coast of Djibouti and passing just beneath me is a whale shark the length of a train carriage. I can feel its back brushing the soles of my feet. Our guide has specifically told us not to touch the creatures. His words echoing in my mind, I scissor my legs to move out of its way – and find myself administering an accidental kung-fu kick to its head.

Thankfully, despite their dinosaur-like dimensions and mouths wider than my bathtub, whale sharks are relatively harmless creatures. The guide’s insistence that we give them space is not because they might choose us as their next meal – they eat mainly plankton – but because they could give us a potentially fatal whack with their huge tails.

Djibouti, a tiny country squeezed by Ethiopia, Somaliland and Eritrea to the rim of East Africa, is a feeding ground for these graceful creatures, which are members of the shark – not whale – family, as well as the world’s largest fish. And for a few months a year it’s possible to go out on a boat, don your snorkelling gear and join them in the turquoise waters of the Gulf of Tadjoura.

Our diving party of around 20 left the jetty next to Djibouti City’s Kempinski hotel about two hours ago. Having never snorkelled before and concerned that Great Whites lurk off parts of the African coast, I wasn’t brimming with confidence about entering the water.

My fear, however, has since been assuaged by the presence of a group of brawny, tattooed US military types from a nearby base who are along for a little R&R. One of them has a diving knife – “I never go anywhere without it, buddy” – which I hope stays in the sheath strapped to his ankle.

Skimming over the choppy waves, we were treated to an offshore view of the harsh landscape, an obliterated jigsaw of jagged black lava. Djibouti has several volcanoes, but perhaps the best known is Ardoukoba, which last erupted in 1978 following an earthquake, having been dormant for 3,000 years.

It took a while to find the whale sharks. Scanning the water around us, we first spotted a pair of dolphins, their silvery backs arcing out of the water. The occasional shoal of fish broke the surface too, causing a ripple of anticipation that quickly turned to disappointment.

Finally we got our first sighting, a nebulous, dark shape in the water about 20 metres away. As we drew closer we could see it inches beneath the surface, a fat torpedo covered in a constellation of white spots. A second, slightly smaller one, appeared moments later. This was our cue to put on our snorkelling masks and enter the water. A first-time snorkeller, I was the last to leap – or rather, gingerly lower myself – into the sea and spent a few minutes swimming on the surface while fiddling around with my mask and mouthpiece to ensure they were watertight.

This is when the French woman on the boat started yelling at me and flapping her arms like Marcel Marceau doing the Harlem Shake. It’s too late though as the whale shark passes right underneath me and, to my relief, reacts to my kick with the indifference of Mike Tyson getting slapped by a flea. Still, I’d be lying if I said I didn’t experience a moment of heart-in-mouth terror.

A few minutes later, I’ve got this snorkelling lark sussed and I’m competent enough to follow the whale sharks with the rest of the group. We swim beside them at a respectful distance, their mouths occasionally gaping open like the entrance to a cave. Seeing something this big move so serenely in such a well-preserved environment – the corals on the seabed intact, water visibility excellent – is an incredible sight; the aquatic version of a condor circling the snowcapped peaks of the Andes.

Each time they swim too far away, we return to the boat and follow them. They don’t seem particularly bothered by their snorkelling stalkers. They’re the labradoodles of the shark world: lovable, docile and noble. The Vietnamese are so enamoured with them that they call them “Ca Ong”, which translates as “Sir Fish.” Which is excessively civilised, in my opinion.

We round off the trip by anchoring in a quiet cove and enjoy an on-board packed lunch of sandwiches and French pastries. There’s a last chance to snorkel around the boat, which some of us do, eager for respite from the scorching sun. The whale sharks are long gone so we have to settle for the odd manta ray, crabs and other piscatorial delights darting around in the tepid water.

It’s the perfect end to the afternoon, and even before we return to port I am sunburnt and sapped of energy, having swum more in the past couple of hours than I have the previous 12 months.

The following day I head 120 kilometres west of Djibouti City to Lac Assal with a couple of guides from the hotel. Take a tropical lagoon, bleach it whiter than Kim Kardashian’s teeth, add a dramatic mountain backdrop and you have the surreal milieu of Africa’s lowest landpoint (509 feet below sea level). The most saline lake in the world outside of Antarctica, it’s a couple of hours’ drive on a surprisingly smooth two-lane highway that cuts through several small villages en route.

Our group arrives to find a couple of local men with camels resting on the salt flats beside the water. A hawker, his wares on display, attempts to sell us handmade souvenirs, most striking of which are goat skulls encrusted in salt, an effect achieved by leaving them in the lake for a few days. If there were a matching one covered with pepper you’d have the ultimate in food condiment dispensers. Someone should tell Ikea.

You could easily lie back and read a book in the perfectly still water of Lac Assal, buoyant as if your body were made of polystyrene. However the crystallised lake bed is sharp as glass, making it extremely painful to walk on. Wearing rubber sandals or flip-flops in the water is essential.

I spend a blissful hour floating around the lake, treating it like my personal giant flotation tank, until a group of baseball-capped tourists turns up and punctures the tranquillity. I get out and wash off the quick-drying salt with bottled mineral water, lest
I end up like one of the goat skulls.

From Lac Assal we drive a few hundred metres back up the road to look at a tiny hot spring set back in the foot of the mountain, where vivid green algae and tiny fish thrive in the burbling water.

Then we drive for an hour to the forbidding area around Ardoukoba, which looks as though a giant has taken a sledgehammer to a billion charcoal paving slabs and failed to clear up the mess. Our guide seemed keen to show us something called “Tuna Lava”. What could this be, I pondered, conjuring images of fish-shaped rocks. After a clamber over boulders the size of tombstones, he points to a man-sized hole ahead. Ah, that’ll be “tunnel lava”, then. Not quite as unusual as I expected, but I have fun exploring the passages, which always come to an abrupt dead end.

On the way back to the hotel, I am shown a crack in the middle of the road, part of the Assal Rift, a point of convergence between three tectonic plates that’s creating an ever-expanding fissure. Right now it’s widening at a rate of two centimetres a year. In several millennia, the guide explains, this area could be slap-bang in the middle of a new ocean, and Djibouti will surely have been long forgotten. But you can bet those whale sharks will still be around.