Nyiragongo volcano in the Democratic Republic of Congo (DR Congo)

Hidden in central Africa is a fiery lake that seems to have been lifted straight from the pages of Lord of the Rings. It's a portal into the centre of the Earth, where liquid rock reaching temperatures of more than 1000C seethes like soup in the devil's cauldron. This is the Nyiragongo volcano in the Democratic Republic of Congo (DR Congo), whose sizzling pit of fire is the world's largest permanent lava lake, according to volcanologist Benoît Smets, who has studied the volcano for more than five years. The 260m-wide pool of fire, which can be viewed from the caldera rim, contains an estimated six million cubic metres of lava, enough to fill 2,500 Olympic swimming pools or 70 Royal Albert Halls. (Credit: Bella Falk)

Nyiragongo has been in permanent eruption since 2002

Nyiragongo has been in permanent eruption since 2002, making it one of most active volcanoes in the world. As it erupts, scalding lava is pushed up to the surface from a magma chamber deep inside the volcano, where it releases its gas, cools and sinks back down. This perpetual convective motion creates a roaring sound like a rushing waterfall, punctuated by loud gas explosions that shoot scorching bombs of lava more than 10m into the air. "There's nowhere else like it on Earth," said Smets. "Standing on the crater's edge, it makes you realise that the Earth is a living thing and that we humans are very tiny creatures on this planet." (Credit: Bella Falk)

The lava lake is most soul-stirring at night

Sometimes the lava lake is obscured by clouds as the crater fills with a white plume of water vapour, sulphur dioxide and carbon dioxide. At other times the vapour clears, revealing the lake in all its fiery glory and leaving visitors with a warm glow on their faces and an uninterrupted view of the churning lake 700m below.The spectacle is most soul-stirring at night, when the jagged black-and-red patterns of the molten rock shine through the darkness and the burning pool lights up the sky with electric orange light. (Credit: Bella Falk)

Nyiragongo is located in the east of the DR Congo, close to the border with Rwanda

Nyiragongo is located in the east of the DR Congo, close to the border with Rwanda. It looms menacingly over the city of Goma, which is just 18km away."The people of Goma both fear and ignore Nyiragongo," said Ruth Umurungi, Nyiragongo's only female guide and head of tour guides for [Green Hills Ecotours](http://www.greenhillsecotours.com/), which runs trips to climb the volcano. "We know we are living with something that could cause a catastrophic disaster, but we can't live our lives in fear. Nothing will be achieved if we worry about the consequences. The volcano also has a positive side: it attracts tourists, researchers and the media, which creates jobs, helps local businesses and raises awareness of the importance of conservation in the area." (Credit: Bella Falk)

Some locals believe Nyiragongo is inhabited by spirits

For many locals, Nyiragongo is shrouded in myth and mystery. Some believe it's inhabited by the spirits of hell, while others think the lava lake is the entrance to the underworld where the souls of sinners go to burn. The souls of the virtuous, on the other hand, are said to go to heaven via nearby Mount Karisimbi, a dormant volcano in Rwanda with a snow-covered summit. Some people also believe that Nyiragongo's eruptions are caused by the bad spirits being angry, so they make offerings to the volcano to try to appease them. There are rumours that in centuries past, such offerings even included throwing virgins into the crater. (Credit: Bella Falk)

Virunga National Park is Africa's oldest and most biologically diverse protected area

Nyiragongo sits just inside [Virunga National Park](https://virunga.org/), a vibrant forest teeming with life that straddles the DR Congo's borders with Uganda and Rwanda. It's the oldest and most biologically diverse protected area in Africa and home to roughly one-third of the world's remaining population of wild mountain gorillas.It's also home to eight volcanoes – two of them still active – which were formed around three million years ago by tectonic forces in the Earth's crust.The source of all this activity is the East African Rift, an active continental rift zone that's being created as the African Plate slowly splits in two. (Credit: Bella Falk)

There are usually only between five and eight lava lakes on Earth

At any given time, there are only between five and eight lava lakes on Earth. The reason there are so few is because the conditions required to create one are so unusual. "You need a magma chamber very close to the surface, connected via an open volcanic plumbing system which that will allow the magma to rise up," said volcanologist Kenneth Sims, who has abseiled dozens of times into Nyiragongo's crater to study the fiery lake close up. "You also need the lava to be the right consistency: this one is less than 50% silica, which makes it runny (lava that’'s higher in silica is much stickier). These conditions are infrequent and difficult to maintain over time. That’'s why lava lakes, especially permanent ones like Nyiragongo's, are so rare." (Credit: Bella Falk)

For the scientists who study volcanoes, Nyiragongo is one of the most fascinating

For the scientists who study volcanoes, Nyiragongo is one of the most fascinating – and the most dangerous. "This lava lake is not only large and unusual, but it’'s incredibly dynamic, often changing from year to year," said Sims. "When I visited in 2010, it was a perched lava lake that stood about 15m above the crater floor. To see the lava, you had to climb this near-vertical spatter cone that was warm enough to make my boot soles gooey and required thermal gloves to grasp onto the hand holds. As bubbles from escaping gas burst through the surface, like a boiling pot of water, the lava splattered way over my head and then splashed back down on the lake in front of me. It was overwhelmingly immense, intensely red, dangerously hot and deeply mesmerising." (Credit: Bella Falk)

To reach the lava lake, visitors must travel to Rwanda and into the DR Congo

Mount Nyiragongo is 3,470m tall. To reach the lava lake, visitors must travel to Rwanda, cross the border into the DR Congo, and then hike to the top – a distance of about 8km with a vertical ascent of just under 1.5km. It takes about six hours to reach the top; hikers then sleep in basic huts on the crater's edge before descending the next day. Due to ongoing conflict in the region, visitors must hike together as a single group, accompanied by armed rangers. It's not a job for the faint-hearted: Virunga park rangers are frequently ambushed and shot by armed militia. In 2020 alone, 14 rangers and four civilians were killed, and security concerns regularly force the closure of the park. (Credit: Bella Falk)

Nyiragongo has had two major eruptions in the last 50 years

Nyiragongo has had two major eruptions in the last 50 years. In 1977, a huge stream of lava rushed out in the middle of the night at estimated speeds of around 30km/h and engulfed nearby villages. At least 60 people died, though some estimates put the number much higher. In 2002, it erupted again. This time a vent (pictured) blew on the side of the volcano and the lake drained, pouring lava onto the city of Goma. Between 50 and 150 people died and almost 15% of the city was destroyed. Thousands lost their homes. (Credit: Bella Falk)

the population of Goma has increased to more than a million

Since then, the population of Goma has increased to more than a million and today the volcano's threat level is monitored as much as possible."It's not a question of if another eruption will occur, but rather when it will occur," said Smets. "Like any other volcano on Earth, we only rely on precursory signals to detect an upcoming eruption. A future eruption may come with such signals, but it may also come without any warning at all. So, nobody can tell when a future eruption will happen." (Credit: Bella Falk)

the best time to see the lava lake is in rainy season

But locals remain undeterred. Roger Kabale Taziviwe is a volcano guide who has climbed Nyiragongo more than 100 times. "Every time I see the lava lake, I feel flabbergasted," he said. "It's as if I'm looking into the centre of the Earth. It really makes me believe that the Earth is a living thing and makes me believe in the wonders of God's creation."Kabale Taziviwe believes the best time to see the lava lake is in rainy season because the clouds that sometimes fill the crater often clear after the rain. "It can be windy and freezing, especially at night," he continued, "but when you are there watching the boiling lava, it's so mesmerising that you soon forget about the cold." (Credit: Bella Falk)