The island of Phi Phi Ley has a 6.6 square kilometres total area - 3 kilometres in length and 1 kilometre wide at its broadest point. The island is entirely limestone and the steep cliffs rising from the sea very nearly completely ring it. Surrounding waters average 20 metres in depth, dropping to 34 metres at the deepest point off the island's southern tip.
The island has several beautiful bays - Pileh, Maya and Loh Samah amongst them. Ao Pileh is very nearly enclosed by the limestone walls of the island's cliffs, so that the water appears almost to be a small lagoon.
On Phi Phi Ley's northeast side is the famous Viking Cave, renamed Tam Pya Nak by HM King Rama IX when he visited it in 1972. The name is taken from the shape of a particular boulder, which resembles the head of the great serpent of Buddhist legends, the Naga. It is a place much revered by the local people who come there to collect the swift's nests used to make Bird's Nest Soup, a Chinese delicacy. On the eastern and southern walls of the cave are coloured drawings dating from historic times. There are pictures of elephants and also of various boats: European, Arab and Chinese sailing ships; baroques, motorboats, and steamships. It is theorized that these were created by pirates who paused in their travels from west to east, sheltering in the cave to escape the monsoon winds, transfer cargo, or make repairs.
There are no resorts or commercial businesses on the island – it's within the area of the National Marine Park boundary which protects the preservation of the lush natural habitat. It is just a few hundred metres from Phi Phi Don, and it's easy to find long tail boat taxi to take you exploring.