Over the past 17 years, I've been studying and writing about whales, swimming with them and getting close to them. But in all those years, I'd never seen anything remotely approaching the awful spectacle I came across the other day when a group of 25 or so killer whales launched a bloody attack on a pod of about 30 sperm whales. Killer whales, or orcas, are perhaps the greatest, most cunning and organised predators on the planet. Intensely agile, they hunt in groups and attack at speeds of up to 30 miles an hour, tearing at their quarry with teeth that are 3in long. Sperm whales, though, are not easy prey. They can grow to more than 65ft and weigh at least 60 tonnes. They're immensely intelligent and armed with tails that could swat a killer whale in an instant. This truly was a battle of the leviathans: one that turned the sea white as the combatants thrashed furiously against each other. And one that left me stunned and in mortal peril. It happened in a national marine reserve off the west coast of Sri Lanka, where, under special licence, we spent the past week patrolling the waters. To begin with, it had seemed like a scene from Eden, with dolphins leaping, turtles mating, flying fish and flying squid. Just half an hour out from shore, we saw the distinctive blows of sperm whales — once the most hunted whale in the world's oceans. Gradually the blows multiplied: ten, 15, 20. Eventually a scientist with us, Ranil Nanayakkara, made an estimate. Around 140 of the world's largest predators were gathering in these warm, clear blue waters. The reason was clear once photographer and film-maker Andrew Sutton and I had lowered ourselves into the sea, snorkelling among a group of five whales. Their grey bulbous heads, shiny under the tropical sun, rose above the water, then dipped down. Inquisitive, they turned on their backs below us. With their eyes set in the sides of their head, it was the way they could see us best. One whale came right alongside us. His eye — about the size of a grapefruit — looked at me with intense curiosity, as if to say, ‘What are you doing here?' It felt like an immense honour to share the water with these whales. Also, a bit intrusive! They had their minds on other things. These animals were responding to spring and mating, en masse, rolling around one another, touching fins and tails. But after we got back in the boat, we began to notice a sharp change in their behaviour. A large number of male whales were grouping together and moving fast in one direction — away from us, to the north. We followed in the boat. We assumed they were being drawn together for what might be the world's biggest animal orgy. Even with our fast boat, we could barely keep up. The other whales were now far behind and widely spread out. Meanwhile, this breakaway pod had slowed down and joined in one great mass, packed as close together as possible — perhaps 30 of the massive beasts lying like logs. I saw sharper dorsal fins moving in and around the great whales. ‘Dolphins,' I shouted. Often, dolphins associate playfully with their huge cousins. Sometimes they hope to get titbits of food if the sperm whales have just returned from a foraging dive. Andrew and I jumped in again. But this time we'd made a mistake. And it could have been a lethal one. Those dorsal fins belonged not to dolphins but to killer whales. Sea wolves. A pod perhaps 25-strong were swimming round the sperm whales, as if rounding them up. The killers started attacking the sperm whales. I saw what looked like blood spilling into the water. This was definitely no place for humans. The orcas' shrill hunting whistles combined with the sperm whales' deeper sonar clicks. The two were locked in a titanic battle. It was very scary indeed. Andrew is not a man who's easily frightened. He's 6ft 2in and has 25 years' diving experience. But he shouted: ‘Out of the water! Now!' I gripped onto his sturdy shoulder, almost frozen by the fascination and fear of what we were seeing. A split second later, we were swimming as fast as I ever had — with a whale on our tails. Was it seeing us off? Or was it about to bite? No killer whale has ever been recorded killing a human at sea, but there's always a first time. We clambered onto the boat, and, for the next hour or more, we stood, with the rest of the crew, on our tiny vessel and watched. It was clear now that the breakaway group had responded to sperm whales who were in danger and had sent out urgent sonar signals. They'd been delegated to deal with the situation — perhaps even to act as a decoy to allow the sperm whales they'd left behind to get away. We watched the orcas' fins circle round and round these brave sperm whales, diving in among them, trying to separate the smaller ones and the calves. The water at the centre of the great whales turned white as they deployed their own most lethal weapon: their tails. Their bodies are two-thirds muscle, and they can wield their mighty tails — as wide as a car is long — smashing them down on their attackers. In the old whaling days, these tails were called ‘the hand of God', because they dispatched men into eternity. This was nature at its most raw: a life or death struggle. The sperm whales defending their most vulnerable. The orca trying to feed their own families. I began to get emotional. Seeing the beauty of both species so close together and in such numbers was completely undercut by the imminent slaughter. Killer whales are so-called because they kill whales — and have often been known to attack sperm whales, despite being a third of their size. The orcas' assault was relentless. Again and again they lunged, trying to bite their way through the great wall of whales. The sperm whales had their own strategy, though; a new tactic. They drew into a new formation, turning head to head in a circle, their ferocious tails facing outwards — like a wagon train in a Western movie. And for a while this ring of whales held out. But as the orca seemed to be getting among them, the sperm whales' circle broke up and they assumed their lateral ranks again, their huge mouths with the biggest teeth in the animal kingdom opening and closing. I caught my breath. Were the orcas about to claim their prize? They seemed to be wearing down the sperm whales' resistance. I couldn't bear it. Close to tears, I shouted at Joseph, our captain, and first mate Manura to turn the boat. I was afraid we were complicit in the killers' attack, blocking off the sperm whales' escape route. Then I quickly realised how wrong I was. In fact, the huge animals had started to use our boat as a block against the remorseless assault. They were lying alongside us, close to the side of the boat. We had became a wall of defence. These creatures have the largest brains on the planet. They are as highly socialised and organised as the orca. They are usually very placid; almost timid. But, when necessary, they employ their own cunning. And their tactic seemed to be working. Slowly, the orca attack began to lessen. Those large male sperm whales, with their armour-like blubber 2ft thick, were defeating the lacerating teeth. It seemed the outer whales were even prepared to sacrifice themselves for the others. They lashed out with their huge, muscular tails, thwacking the water and discharging clouds of red faeces to distract and disconcert the orca. Their sheer staying power, their stamina, combined with their loyalty, had presented the ultimate defence. The orca seemed to realise that they themselves might be in deadly danger from the whales they were trying to predate. We were all hyped up, shouting and swearing, the adrenaline running through our bodies. I felt a huge sense relief as the orca peeled away, and it seemed that the whole extraordinary episode was over. We began to sail off, almost congratulating ourselves in having played a part in saving the sperm whales. But as we left the scene, we saw the orcas up ahead — and it was they who were smashing their tails down on the water now. Either they were playing, or they were venting their frustration. Then they turned — and began to circle us. Again and again. Round and under our boat, which, at 19ft, was dwarfed by them. Suddenly we were as vulnerable as the sperm whales we had just left. It is always hard, if not impossible, not to invest such sentient animals with anthropomorphic qualities. But these whales seemed bent on revenge. Someone said the classic line from Jaws: ‘We're going to need a bigger boat'. But this was no joke. As we watched, fascinated and appalled, they swam in pairs, then in threes and fours, away from the boat but then continually coming back to us. What did they want? Suddenly, they seemed to lose interest. The pod circled us one last time, then disappeared. We relaxed. Too soon. I was looking over Ranil's shoulder when I saw them. Five orca, lined up in a row, coming directly at the side of the boat. It was an intentional and very definitely aggressive act. Remember that scene in David Attenborough's Frozen Planet when a pod of orca co-operate to drive a wave at an ice floe and tip a seal into the sea? Well, that's what this lot were trying to do to us. I'd been scared in the water — but not half as scared as I was now. Then, at the last minute, they dived under the boat. En masse. Why? I don't know. Perhaps they'd been using us to show their young how to hunt and the lesson was over. We realised it really was a lucky escape. As the last killer drifted into the distance, Ranil remembered his hydrophone, which he'd had in the water to record the whales' sounds. He pulled it up. It had been bitten clean off.
