One of the region's best short hikes, the Lushui Trail in Taroko National Park offers gorgeous vistas in both sunny weather and, as the two images below show, when conditions aren't so kind. Long stretches of the 2km-long trail are in forest, so you're never far from shade, which is important at the height of summer. There's also a crudely-cut tunnel; it's so short it doesn't matter if you've forgotten your flashlight, but taller individuals should take care not to scrape their heads on the ceiling.
Some visitors decide to skip this trail when they discover they must either retrace their steps, or march back along the road to where they parked your car or motorcycle. In my opinion, the trail is so attractive it's worth allotting the time and energy to do it both ways. You'll get different views, and you've a better chance of glimpsing endemic Formosan macaques.
No permits are needed for this trail, and the faint of heart can attempt it safe in the knowledge no section is nearly as precipitous as the Zhuilu Old Trail.