It was an unusual, eerie, encounter.

It was an unusual, eerie, encounter. In cold water, greened by plankton blooms, the sperm whales were milling round. Slowly, ponderously, some were sinking head-first and disappearing into the haze beneath me. Others were rising from the depths, rejoining those on the surface, then dissolving away into the distance. Two, each probably weighing between 20 to 25 metric tons drifted in from behind me, so close that their sudden bulk, appearing at my shoulder startled me. Constant chattering – strings of clicks and creaks – passed between the whales. One phrase, if such a human term is appropriate for describing sperm whale communication, seemed to be recurring. ‘Zizzzzzz…tuc tuc tuc”, is the best I can do at replicating it on paper. Louder and more sharply defined, it was, perhaps, emanating from the largest whale, a cow close to 11 metres in length. This cow appeared to be the centre of attention. The others, females and adolescents of both sexes, began aggregating around it.

Earlier, from the boat, we had observed a single large cow lob-tailing; raising its flukes to the sky and repeatedly bringing them down to bash the surface of the sea. On a whale this size, those flukes can weigh around two metric tons-about as much as a large four-wheel drive SUV. And so, each impact of flukes on water generated a resounding whooomp! that would have been audible for long distances underwater, and sent shock-waves of white spray flying into the air.

We had watched through the morning as small groups of whales had congregated on the surface, off the Azores. Sperm whales typically spend ten to fifteen minutes on the surface between foraging dives. On this day, in calm seas, under low cloud, numbers of them were laying on the surface for hours, side by side – “logging” as this behaviour is called. At one time, we could count seventeen whales in one group.

Now, snorkeling in the water, I could see the flukes of this largest whale clearly. It was the same cow we had observed from the boat. After swimming past me, it sank quite quickly, head first, until it almost disappeared.

This was not a dive. There had been no final head-raised breath that characteristically signals the beginning of a sperm whale’s profoundly deep descent. They’ve been recorded reaching depths of around 3000 metres in their hunts for squid, octopus, and fish.

We don’t know how they regulate their buoyancy. There’s certainly no gush of bubbles issuing from their blow-holes as there is when a scuba diver sinks by dumping air from a buoyancy vest. Nor do they have the scuba diver’s reserve of compressed air for re-inflation. But, by one imperceptible means or another, they seem to be able to control their orientation in the water with ease, and, as I watched, the large cow arrested its descent.

Other whales began to cluster around it. They remained in this formation for some minutes. Two or three individuals peeled away. Others moved in.

Eventually the assemblage sank deeper than I could follow by free-diving and disappeared from view. The water around me, more than a thousand metres deep, was empty. Only the distinct static that is the so-far unbroken code of sperm whale conversation, if that’s what it is, continued unabated.

Later in the afternoon, with the clouds now lifted, a group of whales wallowed on the surface, up sun, not far from the boat. In water clouded by those dense blooms of plankton, and against the strong light, it was difficult to identify individual whales. But one unmistakable feature was visible; the curled and floppy flukes of an infant whale, recently emerged from the womb of its mother.

So, was this what the day had been all about? Had we witnessed some form of ritual surrounding the birth of a sperm whale? Had the lob-tailing cow been summoning the clan for the event? Had far-flung individuals gathered to greet the newcomer? Were they now dispersing to relay the news?

We don’t know.

We had observed comparable events some years previously, some 250 nautical miles west of this latest encounter: a large lob-tailing cow whale; a brief but intense gathering of whales; new-born whales in the area within hours of the lob-tailing.

Writing in the late 1700s, French scientist Rene Lesson ruefully observed “What an impenetrable veil covers our knowledge of cetacea! Groping in the dark, we advance in a field strewn with thorns.”

It is still true today. The observations described above might be connected. They might not. In providing us glimpses of their lives, these enigmatic animals, the world’s largest toothed predators, leave swirling in their wakes, not just sheets of sloughed skin and detritus, but hosts of unanswered questions.

Note: Photographs taken under permit issued by Secretaria Regional do Mar, Ciência e Tecnologia with precautions taken to avoid disturbance to the animals. Swimming with whales is forbidden in the Azores without written permission of the Secretaria.

All the photographs we take are made available free of charge for any non-commercial uses related to research, education, or conservation. We routinely share them with whale and cephalopod scientists in various parts of the world. For access to these shots, please click here to contact us.