Xiaoyoukeng

Xiaoyoukeng is the most visited corner of Yangmingshan National Park, and the reason is simple: from the parking area you look straight onto a collapsed slope where fumaroles hiss and roar, yellow sulfur crystals coat the rocks, and boiling water trickles out of the ground. It sits at about 800 meters on the Yangmingshan-Jinshan Highway, above Datong Bridge, and doubles as one of the trailheads for Mt. Qixing, the highest peak in the Datun volcano group.

Nothing here is for soaking. Stay on the boardwalks and viewing platforms, because the ground near the vents is unstable and the gas is sharp in the throat. Plan it as half of a volcanic day out: hike the Qixing trail, then come down to the free baths at Lengshuikeng or the hotel baths in Beitou.

Fog rolls in quickly, so clear mornings from autumn to spring give the best views. The downside is crowds and weather: on a holiday weekend the car park fills early, and on a wet day the whole scene can vanish into cloud. If you are sensitive to sulfur smell or have breathing problems, keep your visit short.