Lake Malawi is an inland sea 580 kilometres long, filling a trench of the East African Rift and dropping to 706 metres deep. From most of its shore you cannot see the other side, and the water is clear enough to read a fish twenty metres out. It holds more species of fish than any other lake on Earth — at least 700, by some counts over a thousand, and almost every one lives here and nowhere else. Nearly all of them are cichlids, small and violently coloured, and they crowd the rocky shallows in numbers that make a freshwater lake look like a reef. David Livingstone reached the lake in 1859 and called it the Lake of Stars, for the lanterns of night fishermen scattered across the dark. In 1984 the clear southern shore around Cape Maclear became a UNESCO World Heritage Site — one of the first parks anywhere created to protect fish rather than land.
Wade in off a rocky point and the water becomes an aquarium: cichlids hang over the boulders an arm's length away, and at Cape Maclear a mask and a few metres of depth are enough to join them. Above the surface the lake keeps its own clock. Fishermen slide out at dawn in dugout canoes cut from single trees, and after dark the far shore lights up point by point. The water is clearest and calmest in the dry season, roughly May to October; wind and chop build most afternoons. Boats cross to Likoma and to the granite domes of Mumbo and Domwe. This is a working lake that feeds millions, and it is under real strain from overfishing and a rising population. The parasite bilharzia lives in parts of it, so people ask locally before they swim.