Gondola

The Boiling Rock has two gondolas that move between the prison and the mainland, via a pulley system. They are used to transfer new prisoners into the prison, as well as shuttling prison guards back and forth between their shifts. There are two separate gondola tracks that run parallel to each other and in opposite directions, so when one gondola car is at the prison station, the other car is at the outer crater station, and they pass each other at the midpoint. The gondola cars are large and enclosed with open windows. The gondolas are the only way off the Boiling Rock, which is why Sokka uses them during his final escape attempt.