The Walls of Alcatraz Had Already Begun to Fade
The crew was aided in their seemingly impossible endeavor by the fact that Alcatraz's walls were already eroding in various ways. Because of the island's proximity to the sea, rust was a common problem. The salt was deteriorating the pipes in the shower and the kitchen. Over time, the concrete in the jail walls began to loosen due to the leaking pipes. This made digging simpler for the gang.