ACCORDING to Dante, the Styx is not just a river but a vast, deathly swamp filling the entire fifth circle of hell. Perhaps the staff of New Scientist will see it when our time comes but, until then, Lake Natron in northern Tanzania does a pretty good job of illustrating Dante's vision.
Unless you are an alkaline tilapia (Alcolapia alcalica) – an extremophile fish adapted to the harsh conditions – it is not the best place to live. Temperatures in the lake can reach 60 °C, and its alkalinity is between pH 9 and pH 10.5.
The lake takes its name from natron, a naturally occurring compound made mainly of sodium carbonate, with a bit of baking soda (sodium bicarbonate) thrown in. Here, this has come from volcanic ash, accumulated from the Great Rift valley. Animals that become immersed in the water die and are calcified.