Nyiragongo volcano, DRC

Nyiragongo volcano, Congo - darkometer rating : 9 - One of Africa's (and the world's) most active volcanoes, located in the Democratic Republic of Congo , and one of only a very small handful that features a (near) permanent lava lake in its crater. In fact this is currently the most active lava lake in the world – and it's surely one of the greatest shows on Earth put up by Mother Earth herself … although many would say it's more like staring into the mouth of hell (cf. Darvaza ). The present lake has formed within the concentric terrace remnants of larger previous lava lakes, which drained in the eruptions of 1977 and 2002, respectively. The present lake is some 250 m in diameter and lies ca. 550 m below the crater rim. The depth of the lake varies, and is believed to have been as much as 600 metres at times, though currently it is certainly less than that. The crust forming on the surface is thin and constantly breaking and shifting, which makes for a zig-zagging pattern of orange in between the black. Exploding bubbles of lava frequently throw material about, sometimes as high as onto a ledge above (though never high enough to endanger people watching the lake from the crater rim). Gas vents from the bubbles – which at the same time keeps the show going. Thanks to prevailing easterly winds, though, the viewing point on the crater rim is often unobstructed. It's obviously most spectacular at night when the red-hot lava glows the brightest. The glow of the crater can even be seen in the surrounding area from many miles away. Apart from being an infernal spectacle of the very highest order, Nyiragongo has also earned its classification as a dark site in the natural disaster department: its eruptions have affected the nearby town of Goma , killing dozens if not hundreds of people and leaving tens of thousands homeless after lava flows engulfed part of the town's residential areas.