The Tianchang Diju Waterfalls Group (中文版： : 天長地久瀑布群) ) is a double waterfall in the Zhanghu Scenic Area (樟湖篇）of Yunlin, Gukeng Township (雲林縣古坑鄉). Together they mean "Everlasting" waterfalls. They are on the same trail as Lingquan Tengjiao (靈泉騰蛟) and Changchun Waterfall (長春瀑布). The hike is only around 5-10 minutes.
Dijiu Waterfall (地久瀑布) is the first waterfall on the trail. It's a nice waterfall, tall, waterfall. But there is a concrete irrigation ditch built into the pool, which diminishes from it's beauty somewhat.
Above Diju Waterfall (地久瀑布) is Tianchang Waterfall (天長瀑布). It didn't have any water when I went in February. But it likely has a lot in Summer and Autumn. I think it will be possible to swim there in the summer as well.
Tianchang Waterfall (天長瀑布) is immediately adjacent to Lingquan Tengjiao (靈泉騰蛟), and 3 minutes from the top of Changchun Waterfall (長春瀑布)
I've never been to the bottom of Changchun Waterfall (長春瀑布) waterfall but under Dijiu Waterfall (地久瀑布) there is another waterfall and swimming hole.
Road 149甲 is broken on the west side of the waterfall. It can be hiked, but not driven. You can get to the top of it from that direction (萬年峽谷) but the road doesn't go all the way through to the bottom. You'll have to drive around from the east side, or hike an extra 2.5km.
Tianchang Dijiu Waterfalls Group
Yunlin County, Gukeng Township
Parking: 23.59977, 120.6569
Dijiu Waterfall (地久瀑布):23.59619, 120.65741
Tianchang Waterfall (天長瀑布): 23.59611, 120.65778
Detailed Map: https://goo.gl/DoBKj