Series turns spotlight on undersea stars

Moving pictures

One of the most comical sequences in the first episode consists of a spy getting involved in an elaborate ritual between hermit crabs, where they swap shells that they have been living in, and so convincing was the spy that another crab took its shell and walked off, unwittingly carrying the concealed camera.

"That moment was something we could never have expected," said Williams. "It's things like that that take you totally by surprise and make it so rewarding filming."

Gordon picks out larger robots for some of his most memorable sequences.

"With humpback whales, often a mother will rest on the seabed while baby plays up at surface level where she can keep an eye on it," he said.

"When our spy dolphin and whale came along, she could see them and didn't mind, so not only did we get interaction with the baby but it didn't affect her behavior at all. We also had a sequence showing a mother and baby sperm whale communicating in a way you would ever get with conventional filming techniques."

The amount of time and money needed to make such films means that increasingly they are becoming international coproductions, with the resources coming from broadcasting outlets and media groups around the world.

Gordon said this was not only helpful for production, but also made for a better creative process.

"Virtually every shoot I went on in this series had people from all over the world on it, all of whom bring different knowledge of the animals and the environment, and also different perspectives," he said.

"There's one cameraman we worked with in Mexico who said how people there view nature and wildlife completely differently to people in the United Kingdom. And this sort of collaboration helps make these series what they are."

This series only dips its toe in the ocean of potential submarine stories that are out there for the spies to discover, and Williams hinted that there may well be more to come.

"There is definitely more mileage in the spy concept, but what's key is innovation and using the latest technology to get spy images," he said. "Cameras are changing all the time, one of the keys to the success of this was incorporating new 360 degree cameras. As long as the technology is changing, there is always room to make these programs better."