I visited Ainsworth Hot Springs in July 2014. This is a charming commercial hot spring pool that is about an hour drive, on a very curvy road, north of Nelson, BC. The most interesting aspect of this location, for me, is the CAVE.
The source hot spring flows in through the back of the cave, so the further one walks towards the back of the cave, the steamier it gets. One can sit just outside the cave and enjoy the hot spring water. Adjacent to the cave and hot pool is the cold plunge, a small pool where one can refresh oneself with a quick dunk. The larger pool receives filtered water from the hot spring, and is closer to warm in temperature–on a hot summer day, it still feels a bit hot though, so the cold pool is a nice distraction.