1.5 hours.
Nan'ao North River is notorious for suckholes and high water flow all year round. Yilan faces right against Northeast Monsoon, which brings a lot of rain in winter, making it difficult to find the right time to visit Yading Hot Spring. It takes several days for the water flow to get low enough to a safe level after rain. The currents are strong and the river is full of suckholes; getting washed away can easily lead to a lethal result. Best time to Yading: February~April
Helmets, life jackets, river tracing boots, a floating rope > 30 meters, and other equipment.
The ending GPS spot is Yading Hot Spring(芽丁溫泉). There are two main outcrops: one at 24.54555,121.73037 and the other one at 24.54496,121.72239. The former's heat source's water temperature is around 60 degree Celsius, and the latter's is around 40 degrees and is a hot spring waterfall.