Sezam was an island situated in a remote corner of the Sea of Death on Skaro.
It was formed by a volcano in Skaro's prehistory, with the molten lava being shaped by the ocean's fierce winds and waves to create a maze of smooth towering walls. In its existence, no Daleks were able to navigate Sezam's canyons.
The Anti-Dalek Force took a photo of Sezam using a satellite and encouraged a recruit to find a route through it. (GAME: The Island of Sezam [+]Loading...["The Island of Sezam (game)"])