This narrow island that acts as a buffer to the harbour and extends down the city coastline makes for a lovely day trip from the mainland. The main attractions are Tianhou Temple, Cihou Fort, a lighthouse and a frenetic seafood street (Hǎichǎn Jiē) where you can get dishes for NT$60 to NT$250. There's also a tunnel through a mountain that opens onto boulders and the harbour, Cijin Beach and a picturesque coastal park with wind turbines.
The beach on Cijin Island is just a five-minute walk from the Cijin Ferry Terminal. When going in the water, be aware that there are serious rip tides along the more-open parts of the beach.
Cycling around the island is about 15km and takes four hours. The bicycle rental shops near the ferry terminal will let you have a vehicle for NT$100 a day.
You can also take your own bike over on the ferry (NT$20 to NT$40), which runs from 5am to 2am between the Gushan Ferry Terminal and the Cijin Ferry Terminal. On weekends, holidays and daily in July and August, a new ferry service runs from Warehouse 2 in Pier-2 Art Center to Cijin.