The Bay of Mali Ston separates the peninsula from the Klek peninsula of Bosnia and Herzegovina and from the Croatian "mainland". The Strait of Pelješac is located at its far western end, and it divides the peninsula from the island of Korčula. In the western part of the peninsula is the highest summit of Pelješac, the Zmijino brdo mountain (lit. Snake's Hill) with the peak Sveti Ilija at .
