The tunnel is pretty cool to see, although it will not take up much of your time as there's not much there. However, in the winter months there are just a few tourists and it's very peaceful, which makes it more worth going. Just south of the tunnels is a quiet beach and decaying military bunkers. Oh, and it's free, but all the attractions on Kinmen are free :-D
dinaliao
worth to see this historical military point. There are mary steps and uphill walk.