The inside of an active volcano, complete with bubbling lava and toxic gasses, has been filmed up close with a set of helicopter drones that have GoPro cameras attached to them.

Explorer Sam Cossman operated the cameras to record high-definition images of the Marum Crater in Vanuatu.

In a video for National Geographic, the helicopter drones were flown over the 7.5 mile-wide caldera. Two drones did not make the journey, succumbing to the extreme environment, but the rest were retrieved providing an insight into the inner workings of active volcanoes.

Marum Volcano, located on the Pacific Ocean's Ring of Fire, is home to one of the world's seven permanent lava lakes. Cossman had to wear a custom built heat suit to protect himself from the boiling lava below.

Listening to the deafening splashes of molten rock was like listening to the heartbeat of the planet
- Sam Cossman

Speaking about getting so close to the volcano, he said: "It's an out-of-body experience where your brain has a hard time processing what your eyes are seeing. Blasted by the intense heat... of a roiling lake of lava the size of a football field from just 15m away, I found myself contemplating my own mortality.

"Listening to the deafening splashes of molten rock was like listening to the heartbeat of the planet. While I was perfectly aware of the danger, it was hard not to be mesmerised by the rare chance to experience the incredible energy of the Earth's underlying forces."

Cossman pointed out modern technology – like the helicoper drones used – provides huge benefits in exploring our planet.

He said: "The drones enabled us to navigate around the gas plumes and perpetually shifting clouds [something that satellite imagery is unable to do] to shoot a series of thousands of images which could be stitched together with photogrammetry software to create the first true to scale, 3D model of a volcanic crater and lava lake."

"With drones and GPS, we are able to reproducibly report real-time measurements and dimensions of the crater and track change over time, which improves our knowledge of the volcanic process."