Green Island's windswept northeast corner was completely out of bounds for much of the 20th century, occupied by a large prison camp. Here, political opponents of the regime were incarcerated and 're-educated' during Taiwan's White Terror and Martial Law periods (1949–87). Most of the watchtowers and chillingly banal buildings still stand, now forming a sprawling memorial museum. It's well worth a visit, but pick up the free explanatory leaflets as little else is in English.

　　Directly east of Gongguan harbour, the first related site is a beautifully manicured lawn containing an excavated trench in which is the National Human Rights Monument. Fronted by photogenic, wave-lashed rocky spires, views from the park are memorable. Around 200m beyond, the most obviously prison-like structure was sardonically referred to as Oasis Villa (綠洲山莊; Shānzhuāng). Here you can peep into the forlorn, mostly featureless jail cells. However, rather more interesting (if less visited, 300m further east), is the New Life re-education camp, where two of the timber-walled halls demonstrate living conditions of the time using waxwork mannequins.

　　If you continue 800m further along the coast, the road soon degenerates into a rough stoney track, passing razor-wired old walls and a 'water torture' pillbox before dead-ending at a lonely little graveyard for some of the '13th Squadron' (ie the prisoners who succumbed). It's a sombre but scenically memorable spot. Walk another 400m along the beach past scuttling crabs, then climb a short rise to reach a large cave full of swooping swallows. This was once used as theatre in which inmates rehearsed and performed re-education plays to demonstrate their new-found faith in the regime. Some say it was also used as an execution ground and mortuary, and consider it haunted.