You don't!
it is the skull with the cavity on it.
There is no key card in skullduggery island.
do you mean skullduggery??
skullduggery island!
its the teeth on the skull
The 13th island of Poptropica was Skullduggery Island, released on June 17, 2010.
You don't climb it. You have to find the cannon starting kit and explosives barrel on that island and push the TNT under the yellow tooth of the skull, fire the nearbye cannon and the map piece will be where the tooth was.
5128904
you can get one on skullduggery island
Skullduggery Island, the 13th island of Poptropica, was released to paid monthly members on May 20, 2010, and to general free play on June 17, 2010.
If you look at the island in the middle it is to the right of it
the fort tower is on the middle island.