On the way to Port Arthur Historic Site on the Tasman Peninsula is Eaglehawk Neck, a narrow 30 metre-wide isthmus that join the peninsula to the rest of Tasmania.
This isthmus was once guarded by a line of ferocious dogs to prevent convicts escaping across the Neck from the nearby penal colony. The slightest disturbance would set the dogs barking and alert the soldiers. (There were dogs on platforms in the water as well).
The convict bushranger Martin Cash was one of the few to escape the dog line – twice, earning him considerable prestige amongst his peers.
The area also included a guardhouse, a store, a jetty (the remains of which can still be seen) and military barracks for the soldiers living here.