of the facility, and taking advantage of them. This may include the discovery of overlooked security issues, or taking advantage of guards who are not following policies or procedures, or are otherwise not doing their jobs properly. Exploitation of corruption Taking advantage of intentional wrongdoing on part of prison staff. This may include the use of weapons or other contraband smuggled in by staff, or receiving assistance from staff who assist due to their personal initiative or by other means of compensation. Failure to return Some lower security inmates are permitted to leave prison grounds temporarily on the honor they will return. These include those who depart for employment outside the facility or furloughs that allow time outside for periods of time. Escape from outside Breaking while in custody outside facility grounds. Prisoners are often transported for work duties, to be moved between facilities, attend court hearings, for hospitalization and medical appointments, and other reasons. Outside help Receiving aid from an accomplice outside prison walls, including those who provide a ride to the inmate following their penetration, smuggle in contraband as visitors, or use helicopters, among other methods. When a banned item is smuggled, it can either be slipped through or tossed over the fence from outside, hidden in a gift to the inmate that is legal, or slipped past corrupt security officers. In some cases, the staff are the source of the smuggling themselves. Escape from island prisons Escaping from an island prison brings another challenge of crossing the water to free land. This can be done by construction of a makeshift raft or receiving outside help from the owner of a boat. In the famed 1962 Alcatraz escape, a makeshift raft from raincoats was confirmed. One additional theory is that a boat was used to transport them in the water. Prevention Prevention of prison escape includes the numerous security measures that are in effect. How many and which measures are used depends on the security level and specific institution. Some of the preventive measures are: Structural One or more fences surrounding the facility Barbed wire or razor wire on topping fences that surround the facility Razor wire on the ground between fences, thereby making one's presence in this area dangerous and possibly deadly Multiple locked doors between the "pods" (sections of cells) and the exit Cell windows made too narrow for a human body to fit through; iron