Sun Moon Lake is named for a shape that has not existed since the 1930s. Taiwan's largest lake sits high in the mountains of Nantou, and until Japanese engineers dammed it a wooded island stood between two halves of the water, one round, one a crescent. The dam raised the surface some twenty metres and drowned all but a stub of the island. What is left of the shape still reads from the ropeway you ride out of the village of Ita Thao, hanging over the treetops. From the top of the arc the broad eastern basin that was the sun sits on one side and the moon's narrower western arm on the other.
The island is Lalu, and it is sacred to the Thao. Boats go round it but tie up only at floating platforms set in the water; the ground itself stays closed. From the rail you can pick out the bishopwood the Thao planted on it in 2000 and a Japanese-era stone tablet still standing in the shallows. Big carved owls stand on the platforms; the Thao count the bird a blessing on a house expecting a child. Two temples on the old shoreline were condemned by the rising water, so their congregations took the compensation, pooled it and built one temple higher up. That is Wenwu, on the north shore, where the lake runs away from you end to end past its red-and-gold gate. Mornings are the reason to stay the night. On the boards at Shuishe pier, before the first boat starts its engine, the mist lies on the water in sheets with the mountains flattened into grey layers behind it. Swimming is banned every day but one, when more than twenty thousand people cross three kilometres from Chaowu pier in the largest mass open-water swim held anywhere. The rest of the year the lake is working. At peak demand its water falls through the turbines below, and at night, when power is cheap, the same machines run backwards and pump it all the way back up.