Nisyros lies to the north of Telos, and is about sixty stadia distant both from it and from Cos. It is round and high and rocky, the rock being that of which millstones are made; at any rate, the neighboring peoples are well supplied with millstones from there. It has also a city of the same name and a harbor and hot springs and a temple of Poseidon. Its perimeter is eighty stadia. Close to it are also isles called Isles of the Nisyrians. They say that Nisyros is a fragment of Cos, and they add the myth that Poseidon, when he was pursuing one of the giants, Polybotes, broke off a fragment of Cos with his trident and hurled it upon him, and the missile became an island, Nisyros, with the giant lying beneath it. But some say that he lies beneath Cos.