June 1962 Alcatraz escape attempt: Escape from Alcatraz
Alcatraz, San Francisco, USA
Once the holes were wide enough to pass through, the escapees nightly accessed the utility corridor left unguarded directly behind their cells' tier and climbed to the vacant top level of the cellblock, where they set up a clandestine workshop unbeknownst to prison staff. Here, with over fifty raincoats among other stolen and donated materials, they constructed life preservers, based on a design one of them chanced to find in Popular Mechanics, as well as a six-by-fourteen-foot rubber raft, the seams carefully stitched by hand and sealed by steam pipes' heat. Having manufactured the raft, they inflated it with a concertina ingeniously rigged to serve as bellows and furnished the necessary paddles from scrap wood and pilfered screws. Finally, they climbed up a ventilation shaft bound for the roof, and, finding a ponderous fan-grille in the way, removed the rivets holding it in place.