That's a prison for the less fancy among us. ... Alcatraz Island was an ideal maximum-security prison purely because, as an island in the middle of the San Francisco Bay, getting out and swimming to shore was thought to be impossible. Hence its moniker as “the inescapable prison”.

Why did they decommission Alcatraz?

Prison Closure

On March 21, 1963, USP Alcatraz closed after 29 years of operation. It did not close because of the disappearance of Morris and the Anglins (the decision to close the prison was made long before the three disappeared), but because the institution was too expensive to continue operating.

Why was Alcatraz so bad?

2. Alcatraz inmates were forced to build their own prison. ... The military transferred ownership of the island to the Department of Justice in 1933, which is when Alcatraz became synonymous with the worst of the worst, housing notorious criminals like Al Capone and George “Machine Gun” Kelly.