This can take a good 4 to 5 hours round trip, possibly more if you spend a lot of time playing at the water slide
When the water is not too high there will be a few small climbs up the sides of waterfalls around an hour or 2 in, even then you will need to swim in some areas. If you're not comfortable with some basic climbing you won't be able to go very far. When the water levels are high there can be fairly strong currents ins some areas, and water flowing over where you need to climb. I wouldn't recommend this as a starter trace or for people who aren't strong swimmers.
Boots, as usual, life jackets if you can't swim well.
A really nice trace within a day trip from Taipei if you wake up early. This is within my top 3-day trip traces from Taipei I would say. The first 20 mins or so isn't anything special, however, once you climb over around the "man-made waterfall" it gets gorgeous quite quickly. There are tons of waterfalls, clean water, great landscapes, cliff faces to the side of you, and you really do feel "in the wild". You will at a certain point reach a fork, we stayed to the right at the fork and continued on till the end. If you wanted you could try left though I am unsure what you will find. At the very end if it has been raining you will find one massive final waterfall. From there you are going to need to backtrack to around the waterslide. From the waterslide, there should be a trail on your left-hand side you can use to get out.