IF THERE’S ONE THING THAT comes to mind when you think about whales, it’s size. The blue whale is the biggest animal ever to exist on Earth. Famously, it also has an aorta large enough to swim down, a fact I originally learned courtesy of David Attenborough’s narration of the BBC’s seminal Blue Planet – now 10 years ago.
But strangely, despite their immense size, one thing I hadn’t realised until working on this year’s TV documentary series Ocean Giants is how little we actually know about whales.
Even the most basic facts such as “how many are there” and “where do they spend their time” are not always known. You’d think an animal the size of a whale would be easy to track down, but with an almost impenetrable mass of water the size of the world’s oceans, its bulk suddenly pales to insignificance.
It’s a dot of spray from a blowhole on a horizon – and there are so many horizons across the oceans that even making sure it’s your horizon requires a good degree of strategy.
Even once found, a whale can be hard to keep track of – able to hold its breath for 20-40 minutes, once a whale sinks into that blue, there may be no way of knowing where it will emerge.
Luckily, there are places on the planet where certain whales congregate reliably every year.
Magical scenes play out, and key events happen in whale lives there. Battles between rival males are fought and lost, dominances are asserted; females conceive, and calves are raised.
For Ocean Giants, I was lucky enough to visit a few of these amazing places, to glimpse the worlds of these creatures before they slip quietly into the concealed vastness of their oceanic homes.

HUMPBACK HEAT RUNS IN HAWAII
Humpback whales can be reliably sighted every year in warm, tranquil waters off Maui, in the Hawaiian island chain. Free of predatory killer whales, the area is a nursery ground for north Pacific humpback populations.
In late October the first whales appear, at the end of an annual migration of more than 3000 miles from their Arctic feeding grounds, where they fatten up over summer.
Peak season is January to March, and as more whales arrive the waters fill with whale song. Even beach swimmers dipping their heads a few metres beneath the surface can hear the ethereal moans and grunts of far-off singers.
Each year 3000-5000 whales take advantage of Maui’s warm waters for breeding and nursing. But lovely as they are, we’re not here to film the serenity of humpback mothers with their calves, but for a higher-energy spectacle – a humpback whale “heat run”.
Like a giant game of swimming kiss-chase, a heat-run forms when a female whale (already surrounded by males) takes off at speed, hotly pursued by apparent suitors, who barge, jostle, and even ram each other in a bid to take their place by her side.
Unlike kiss-chase this is a serious affair, and males are often seen bloody and raw from their collisions.
I say “apparent” suitors, because scientists point out that they have never demonstrated that the run is followed by intercourse. But I’d lay quite a lot of money on it. Fundamentally, whales are mammals like us, and I don’t think all those males are there for a swimming prize.
So, how to film a kiss-chase of 30-tonne whales The whales are heavily (and rightly) legally protected, so to approach close enough to film, we need to work under the guidance of officially permitted and experienced scientists.
Our scientists and boat-drivers Jeff Kalbach and Jill Mickelson have worked in-water with these whales for 15 years, and are an invaluable source of advice on approaching them without disturbing their natural behaviour – and without too much risk. In a battle between 30-tonne bull whales, even a 6ft 4in cameraman is small fry.

WE’RE DOING THE SHOOT on breath-hold. With the whales moving so fast, we need to be responsive to get the shots. With all the added gear and weight of scuba or rebreathers (and associated breathe-up times) there would be little hope of getting the shots.
Most of the action happens in the top 20m, and breath-hold has the additional benefit of not emitting bubbles – which the fighting whales use as a sign of aggression during the chase.
The first day we head out, I’m impressed by the number of whales. With Jill and Jeff as our guides we get off to a good start, filming topside shots of a small run from the boat.
But we fail to get close enough in the water for the shots we need.
As on any shoot, it’s going to take persistence to hone our technique, and time to get the opportunities.
A heat-run can start at any time, with groups of 4-12 whales – and there are even accounts of monster battles of 25 whales taking place far out at sea.
We’re working with other boats in the area, so people know why we’re here, and every so often the radio crackles as a report comes in with the co-ordinates of another run starting up.
We get some lovely footage of a mother and calf in the first few days, but we have to wait quite a while before we get a big heat-run.
Ten days in, we get a call about a run of 12 whales further off the coast. As we arrive we can see that things are hotting up. The whales barrel along, barging, tail-slapping and churning the water to a white broiling mass. In the water, Jeff leads the crew to the action. It’s difficult swimming in the choppy water, especially pushing large cameras, but they make it to the whales and stop a respectful distance away.
It pays off. The footage is impressive as the fighting whales come closer and closer into range, with foaming bubbles and huge swipes of their tails as they use a number of blocks and strategies to try to get close to the female.
The final payoff is when two rival males travelling at speed towards the camera barge into each other in an underwater collision, one releasing a huge blast of angry bubbles in an underwater show of strength.

AMAZON RIVER DOLPHINS
It’s unusual to head inland to film dolphins, but to see the Amazon river dolphins, or botos, we fly more than 2500 miles from Sao Paulo to the heart of the Brazilian rainforest, first landing in the city of Manaus.
From here we take a tiny amphibious aircraft over an endless green sea of rainforest as the Amazon snakes silver below us. After two hours of flying over uninterrupted jungle canopy, we land on a large U-shaped bend in the Rio Negro, near a floating hut where scientist Vera De Silva does her research.
Botos are engaging and fascinating animals. They really are pink, and much fatter and more blubbery-looking than your average bottlenose or spinner.
Unlike their marine relatives, the vertebrae of which are fused, botos have moveable necks, and long, toothy, snout-like rostrums, all adaptations to their forest home.
The tree-canopy over which we flew conceals a water-world, where buttress roots, vines and undergrowth are completely submerged.
Every year, the Amazon and Rio Negro flood their banks and submerge the surrounding forest in 5m of water or more. So as well as hunting in the main river channels, the botos need to be manoeuvrable and able to pick their way through dense submerged tangles
of forest vegetation and roots, where fish take refuge.
With minimal visibility and shorter distances, there’s little call for the high-speed antics of marine dolphins, and the softer, almost flabby-looking skin and lack of fused vertebrae are a resultof this.
Filming the botos in the Rio Negro is fairly surreal – the dolphins are pink and, belying its name (“black river”) the water is orange, although peering in from above so much light is absorbed that the water does look black.
Entering the river is like submerging into well-brewed tea, with the effect of putting a rich tobacco filter over your mask, and the camera lens.
Below a few metres so much of the light has been filtered out that it is completely black. Heading more than a few metres down is an eerie experience.
Botos have enhanced echo-location capabilities to deal with this lack of light (and almost zero visibility in some parts of the Amazon), and listening through Vera De Silva’s hydrophone reveals a complex system of chirps and creaking social noises.
Staying in the sunlit shallows and using only snorkel, we film the dolphins weaving through submerged vegetation, which they are perfectly designed to do.
Turning their heads left and right, going forward and reversing, it’s hard to imagine a marine dolphin coping in this habitat.

SOUTHERN RIGHT WHALES IN PATAGONIA
Patagonia is a spectacular place, and to film southern right whales we journey to Peninsula Valdes, a UNESCO World Heritage site and haven for all kinds of marine life, from sea-lions, elephant seals and orcas to Magellenic penguins and, of course, the southern right whales for which we’ve come.
This time, we’re here to film the act of mating, and for no less reason than that the southern right whale is the proud possessor of the largest testicles in the world – and therefore also the known Universe – as our scientist, Mariano Seroni, is keen to point out.
Our story is about the benefits of being large, and with 1 tonne testicles it seems that for southern right whales when it comes to successfully fathering the next generation size does matter.
Southern right whales exhibit a breeding strategy known as sperm competition, in which the female will mate with several males in an attempt to get the best father for her calf.
No-one has seen the humpbacks of Hawaii mating, but southern rights are gregarious breeders, spending hours in mating groups at the surface.
They’re also completely unconcerned about boats. This trait led to their name, as they were the “right whales” to hunt.
Populations are now recovering from an estimated low of 1200 in the early 1900s to around 10,000 today, though remain far from their pre-whaling populations of 55,000 or more.

DESPITE THE LOSSES, heading out for the first day’s filming it’s apparent that there are a lot of whales around Peninsula Valdes in August.
Our difficulty lies not so much in getting close as in the potential for getting too close. The courtship is more relaxed and peaceful than our humpback encounter, but there is still the distinct danger of getting squashed between whales, or even being pounded onto the seabed in shallow water.
This time we have no in-water guidance from our scientist, who doesn’t normally dive with the whales. It’s cold on the boat, 5-8°C depending on the sun and wind, and the water is a fairly chilly 8°C. Despite this, cameraman Didier opts for a wetsuit to make him more manoeuvrable around the whales.
The whales may not be shy, but while there is a good deal of fraternising going on, witnessing the moment of mating takes persistence. Several times the whales spy-hop and investigate the boat, but we need a good encounter.
At times the groups are very shallow, kicking up immense amounts of sand from the bottom, dropping the vis to a few metres in the turmoil of the giant courtship. In such conditions it’s far too dangerous to film. It’s impossible to get out of the way of an approaching whale, and in any case the shots would not be of a good standard.
Even when dropping into relatively clear water, the speed at which an 18m, 80-tonne whale emerges from the gloom is impressive. The first one I see comes straight to me, and I have to back-pedal as it cruises past, its curious left eye gazing at me intently.
It’s important to keep alert – although they’re not usually aggressive, one careless swipe of the tail could cause serious injury, wind you, or knock your mask off and reg out. Luckily,
our cameraman is used to working with whales and can judge his own safety.
One day, a recently born calf weighing over a tonne cruises straight up to the camera, his mother keeping a watchful eye on her curious giant offspring.
Then, eventually, the vis is right, the sun shining, and the whales are not just courting, but mating.
We finally get the intimate shots we want, and the group stays together for over an hour.
The sequence is rounded off with beautiful footage of amorous whales lolling at the surface, silhouetted against the green surface light, which splays out in shards around them.