Dara Ó Briain’s new two-part series about volcanoes kicks off on 5 tonight. Here he talks about the awesome power of eruptions, the highs and lows of filming, and what might happen if a super volcano goes off… 

How do the volcanoes you investigate in the series differ?

One of the joys of this series is that we saw four different volcanoes and, in terms of their activity, they all behave quite differently. Etna is busy and, when it goes off, it’s dramatic, while Stromboli is open and constantly firing. Vesuvius will do nothing for years and then the eruption will be huge; Campi Flegeri, the other volcano that’s underneath Naples, will sit there doing absolutely nothing for hundreds, or perhaps even thousands of years, and then it will turn insane.

Campi Flegrei’s last eruption was so enormous that if you dig into the soil in Russia, and through various layers of sediment, there will be a layer of volcanic ash from there. That’s how big the eruption was - there was a cloud of ash so huge, which later fell, it dropped the temperature by five to ten degrees and brought about a winter.

Did you find encountering world-ending forces there’s nothing we can do about sobering?

Volcanoes are powerful things, aren’t they? There’s also the knowledge that there is literally nothing we can do about them; there’s no cork we can stick in them and you can’t drain them into the seas or oceans. They’re like spots under the surface of the Earth’s skin, but there’s no Clearasil to remove a reservoir of magma.

When you’re on a volcano you think, ‘This could go at any moment’, but they don’t just go at any moment. What will hopefully come across in the film is how scientists would see an uptick in activity, such as the changing nature of the gases. Even before Vesuvius erupted in 79 AD, Pompeiians had noticed changes around the volcano before the eruption. Nowadays the city would be cleared after those changes had been spotted.

An eruption in a heavily-populated area feels like a historical event, instead of a modern one…

During a holiday in the Caribbean, I was treated to a helicopter flight around Soufrière Hills, the volcano on Montserrat, and you can see the villages which were wiped out by an eruption. That eruption was on an island where the population density is pretty low; Naples is a contemporary city dense with alleyways, burrows, and multi-storey apartment buildings, a place where we haven’t seen lava flow down streets.

How significant is the threat to Naples from volcanic activity?

Naples lies in a basin with a volcano on one side and a super volcano on the other. Volcanoes operate on a timescale very different ours, particularly a super volcano, which is more vast than others and when it goes, it will go big. But that may not erupt within any of our lifetimes, so I’m not going to worry about a super volcano when I have a lot of day-to-day stuff to worry about.

Even Vesuvius, which tends to erupt once every 50 to 100 years, might be dramatic without being dangerous and may just change the geography of the mountain rather than release a pyroclastic flow reaching the population.

How frightening is a pyroclastic flow?

The pyroclastic flow is what you have scientists talking about at the start of a Roland Emmerich disaster movie to set up the eruption, because that’s where the movie kicks off. A flow is a 300℃ current [of gas and volcanic debris] travelling at perhaps 100mph and there’s no escaping one.

In the documentary a professor shows us a pair of femurs, one incinerated and the other untouched, which is because that person happened to be standing sideways to the pyroclastic flow. That’s an astonishing injury. These are an incredibly destructive force and one in a heavily populated area would be a total disaster.

However, as I said, we think of time on a human scale when we live our lives within the gaps of their activity. The volcanoes won’t notice we’re even there and chances are these eruptions might never occur in our lives.

Did you find the examples of pyroclastic flow injuries shocking?

It would be like being in an airlock that’s opened into space - a lot of things happen exactly at the same time, and you’re overwhelmed by everything happening. You’d be done in three seconds, so it’s not a pleasant way to go and there’s not a lot of you left, but it has the benefit of being quick.

There’s one instance of somebody surviving a pyroclastic flow - a prisoner in the Caribbean was in a stone cell facing away from the flow, which killed almost everyone else. He was badly burnt, but the flow didn’t kill him.

You meet Professor Moro, a cultural anthropologist, who explains the presence of Vesuvius has influenced Neapolitans to live their lives in a hurry - did you find that unusual?

I think it's as much as the sense of life is for living and that it might all disappear in a moment. That is a very impractical way to genuinely live, as you'll never do your taxes and nobody gets a pension in that situation. Pension sales aren’t a big job in Naples.

Lots of places talk about how they love life, but you don’t necessarily need to have a giant volcano beside you to feel that way.

How unnerving did you find the constant bangs on Stromboli as you climbed up its slope?

The noise is unsettling because not only are you walking towards where it’s coming from, but also the route skirts the point where the grassy path turns into a cliff of sliding volcanic debris, which you do not want to step on.

Stromboli is a very interesting volcano, because it’s like an open valve straight into hell and every 30 seconds it’s spitting stuff out. When it fires, it is cinema, giving you the shot of a red fountain you want to see.

When dusk appears so do the colours of the eruptions and they are amazing. We would film a piece to camera, then we’d all film the eruptions on our phones, and then we’d film a bit more to camera, because we all wanted to capture the sight, too.

Did Stromboli make you work for the experience of watching its eruptions?

That walk was a proper two-hour schlep and there are no cars on the island, so there wasn’t a Jeep to zip us up the side of the volcano. The walk back down was a little more exhausting as you're walking away from such an amazing place and you wonder if you’ll ever see those sights again.

What was it like spending a night on a volcanic island?

We had such a pretty hotel and the island is so lovely, we thought it would be nice to stay and travel the following day. I was exhausted, too, and the four-and-a-half hours of climbing impressed my Apple Watch and set a new record.

I went back to the hotel, had a beer, and then went to my room to sleep, because I had never been as tired as I was after the climb. I sat on my bed and it was like a door was underneath the sheets - it was the hardest bed, like something a monk would sleep on. It was punitively hard. It was penitentiary hard. It was The Name of the Rose hard. I thought, "You’re kidding me!" I had to make a bed out of the couch.

Was travelling by cable car up Etna worse than being on an active volcano?

Cable cars are the devil’s work. I hate cable cars and it was horrible. The weirdest thing about being on top of Etna is how the enthusiastic scientists would point to part of the volcano and say, ‘That wasn’t there four years ago.’  What’s essentially a mountain is changing the whole time, with even lakes disappearing.

Was walking across Etna’s stark landscape above the clouds an otherworldly experience?

Volcanic soil is the closest parallel to the soil on the Moon, which is called regolith, and scientists used it to test technology like Moon rovers. We left the cable car, and it felt like we were no longer on Earth, as if we’d passed through the clouds and been transported to a distant moon.

Admittedly, the coffee shop in the cable car station sold sandwiches and Twixes, so part of Earth had come with us.

Did Ciro and Steph, the vintners who grow grapes on Etna’s side, seem complacent about where they live?

He’s lived there for his entire life, she’s lived there for 30 years, and they’ve learned to roll with the volcano. They accept, occasionally, they’ll step outside and volcanic soil will be everywhere, including in the swimming pool which the poor robotic cleaner has to tidy up.

But they do make cracking wine. We recently had one of the whites and we’re still working our way through some volcanic wine. The flavour is strikingly different between one field and the other, because the soil is from different craters, so the chemical makeup is quite different.

Was the wine research the best research you’ve ever undertaken?

As an item, I was very happy to give it a try. When I was told, ‘If you drink this wine, you’ll find it different to that wine,’ I thought I would try them for science, and all my years of training came to the fore. The wine was yummy and, because I’m very thorough, I had to go back and try the first one again for comparison. Then I had to alternate between the two for a while. After that, everything was all very nice.

Did you find exploring the inside of a lava tube claustrophobic?

My claustrophobia is very much not being made to go potholing, rather than being in a small room. I don’t like narrow caves but the lava tube, which is incredibly rare, is a semi-circular tube and not a cave in the sense of there being rocky outcrops.

Lava has acted like when you squeeze toothpaste out of a toothpaste tube except, in this case, the toothpaste has created the tube itself. The shape is very regular, created by one of the most destructive forces on Earth, so the lava tube doesn’t look like something created by the normal forces of nature. It was weird.

Did making this series have an element of danger?

Volcanoes are very alluring and you do want to be closer to them to see the red, so you’re drawn like a moth to a flame, but we weren’t too close and the team were very cautious. I once almost died in a river while filming for Comic Relief, so I don’t do danger for the cameras any more.

Was there a part of you that wanted something dramatic to happen when you were visiting the volcanoes?

You kind of do wish for a certain controllable level of chaos, as it’d be amazing for the documentary although not particularly nice for the people who live there. You wonder if the time you’re there will be the time the whole thing goes up. The authorities do have enough of a warning and stop people visiting the volcano, so it’s not as if the peak just goes ‘Boom!’

How much did you enjoy filming in Naples?

Obviously, the food is incredible. The soil is amazingly rich and so the food tradition is superb: they eat well, they drink well, and they live well. Naples is a fun city with a lovely mix of the very old and the very new.

I was walking down one street and a delivery rider stopped in front of me, which is a normal thing to happen. Then a basket dropped down from a fifth-storey window and the rider placed the order in the basket, which was then pulled back up. People have been dropping baskets like that for hundreds of years and now it’s for Deliveroo. Fantastic.

We all fell in love with Naples, as it’s a fabulous place with a real energy and vibe. When we left to film on the last day we stayed in what was essentially a motorway hotel and we were heartbroken.

• Volcano with Dara Ó Briain, airs on 5 on today and tomorrow at 9pm, and will also be available for streaming.