The community of Radium is named after the nearby hot springs in Kootenay National Park. Radium Hot Springs is one of my favourite hot springs in BC, primarily because the main mineral pool is enormous!
For this reason, it never feels too busy. The location is also spectacular, with dramatic rocky canyon walls towering over the main pool.
Radium Hot Springs is a great place to soak sore legs after a long hike. Forgot something to swim in? They rent 'heritage-style' swimsuits. The hot springs facility dates from the 1960s.
A Parks Canada parks pass is required to explore Kootenay National Park ($22/day for a vehicle of up to 7 people).