Thanks to the blog entry below, we now know the point in Taiwan that is furthest from any coast: The Pole of Inaccessibility. Of course, the day I read about this, I knew it needed a geocache! I encourage you to read the blog post to find out how this cartophile (map lover) calculated this precise point.
It's located only about 150 meters from the road that you pass when hiking up Zhushan Sunrise Trail. Note that there is an access fee of NT150~300 for the Ali Shan area. Also note that you must park in the designated parking areas and either hike up, take the little train, or join a tour bus group.
The hike from the closest parking area to the Zhushan Sunrise Trailhead (at Zhaoping train station) takes about 20 minutes. From the trailhead to the Pole of Inaccessibility took me about 30 minutes.
I rated this cache T4/D3 because at the time of publication there was no trail and the hike required climbing and bushwacking. As of 2021 there is now a small path; however, I'm keeping the original rating for posterity. The cache is attached to the tree where the Point of Inaccessibility sign is posted (refer to the links above). It's a small plastic lock-n-lock box, big enough for small TBs and swag. Please bring your own pen.