Viking Cave

Tham Phaya Nak, a 170 metre cave at the foot of the north-east cliffs of Phi Phi Leh, named after old boat paintings on its walls. Edible swiftlet nests are still harvested here under a guarded concession, and the cave has been closed to visitors for years, so tour boats only slow down to view it from the water. Snorkelling along the cliffs nearby is good.

Viking Cave is on Phi Phi Leh, the uninhabited island 20 minutes by boat south of Phi Phi Don.

Not that we know of. This page on kohphiphi-live.com shows what Viking Cave is and where to find it.