Tháng 6 năm 2010, một nhóm các nhà khoa học và những nhà thám hiểm gan dạ đã leo xuống bờ hồ dung nham nóng chảy ở dưới miệng núi lửa Nyiragongo, ở giữa vùng Great Lakes, châu Phi. Nhóm này đã mơ được đi bộ dọc theo bờ hồ dung nham lớn nhất thế giới. Những thành viên trong đoàn đã bị mê hoặc bởi những tấm ảnh mà họ được xem khi còn nhỏ, trong bộ ảnh tư liệu năm 1960 mang tên “The Devil’s Blast”, của Haroun Tazieff, người đầu tiên giới thiệu với công chúng hình ảnh những dòng dung nham nóng đỏ ở đáy miệng núi lửa Nyiragongo. Nhiếp ảnh gia Olivier Grunewald chỉ đứng cách mép hồ khoảng 1m và đã mang tới cho chúng ta những tấm ảnh hết sức chân thực về hồ nham thạch này.

The view from the volcano’s rim, 11,380 feet above the ground. At 1,300 feet deep, the lava lake has created one of the wonders of the African continent.

The permanent lava lake of the Nyiragongo is the biggest in the world, an estimated 282 million cubic feet of lava. In 1977 and 2002, the lava lake breached the crater, destroying a large part of the city of Goma in the Democratic Republic of Congo.

At the surface of the lake, bubbles of gas explode. The surface is permanently churned by fury from the earth's crust.

Even though the lava lake often overflows, the seven members of the expedition yearn to walk its shores.

Mount Nyiragongo is the most active of the eight volcanoes forming the Virunga range.

At the beginning of the descent to the second terrace, falling rocks are a major risk. The gas often blinds the climbers.

To prepare for the expedition, members have undergone four months of training.

Jacques Barthelemy, a mountaineer and veteran of Nyiragongo, uses a rope to bring bags of equipment to the second terrace.

Using a laser telemeter, a member measures the changing size of the lava lake.

At night, the base camp is illuminated by the light of the lava lake.

The goal of the expedition is to reach the rim of the lava lake. Nobody has previously survived such an encounter.

Members of the team keep in contact through radio and relay data about the lava lake's activities and the direction of the gases.

Climbers must determine the best method for descent.

Bubbles of gas explode at the surface of the lava lake.

Franck Pothé approaches the lava. For such a close encounter, the wind must be at his back, pushing the heat away. Pothé is constantly informed of the swirling winds via radio contact with other members.

The first member of the team to reach the lake’s rim.

Encumbered by equipment, Olivier Grunewald must be guided by radio to where he can place his hands and feet.

Grunewald, on the lava lake’s first close-up: "I was so overwhelmed by the spectacle of this surface and trying to take pictures, I had no idea of time, of heat ... suddenly the radio told me that it was time to go, the activity being too close.’’

A major risk is the frequent overflows of the lake. Members surveying the lake from the second terrace help alert others to any threatening lava movements.

At dawn, the light becomes magic, but gases could cover the bottom of the crater in a matter of seconds.

An overflow starts at the beginning of the night. Year after year, the lava reaches higher along the crater walls, until another breach or an eruption empties the vessel. The goal of the expedition is to increase volcanologists’ knowledge and ability to predict such an event and prevent another disaster.