BBC cameramen had already failed once in their attempt to capture the event, a year and a half before, so when Munns and his team set out from the coast of Costa Rica on a three-week mission in a small fishing boat, all fingers were crossed. One thing was certain, though: there would be a lot of hanging around.

“The cruelty of open-ocean filming is the boredom,” Munns explains. “It takes a certain kind of patience and mental strength to stay rational, calm, positive and ready for action when you see nothing but sky and sea for weeks on end. That’s what happened to us. We spent almost three weeks bobbing around in the sweltering heat of the big blue. Finally, at dawn on the penultimate day, we found our bait ball. The whole feeding event lasted less than 30 minutes, but we got the shots we needed of the dolphins, mobula rays, tuna and sailfish feeding on masses of lantern fish.”

Munns’ job requires considerable fitness in the water. He is a qualified diver (obviously), with over 5,000 dives completed, but also a strong surfer, free-diver and open-water swimmer. “I’m always learning, though,” he says. “I never fall into the trap of being blasé or over-confident. The ocean is fickle and immensely powerful.”

One constant headache is travelling with all the film equipment. Born and brought up in the UK (“on the rugged coast of North Cornwall, where I got my love of the ocean”), Munns now lives with his wife and two children in the Malaysian city of Kota Kinabalu, from where he flies to various maritime destinations around the world.

“I’m often checking in at airports with several hundred kilos of gear,” he explains. “Negotiating check-in, customs and security with cases full of sensitive camera equipment and batteries is not in any way fun. Multiple short-haul flights, taxis and boat transfers mean constantly loading and unloading gear, making sure nothing goes missing.”

But, once on location, it’s always worth the effort. The huge exposure of the TV series Munns works on enables him to project an invaluable environmental message to viewers worldwide. Blue Planet II, for example, which was narrated by David Attenborough, has been seen in more than 30 countries.

Munns is proud of the innovation of the documentaries he and his colleagues produce. “We are usually pushing the envelope in terms of equipment, scientific knowledge, animal behaviour and cinematography,” he says. “Often I’m filming something which has never been filmed before. I’m not just trying to capture it on camera; I’m trying to make the shots worthy of David Attenborough’s voice.”