Mount Rainier at 14,410′, is an active volcano that formed around half a million years ago. It is part of the Pacific Ring of Fire, a region known for its high volcanic activity. Rainier is a stratovolcano, indicating its explosive potential.While Mount Rainier is considered dormant, it’s still an active volcano. The last significant eruption occurred over a thousand years ago, but scientists closely monitor the mountain for any signs of renewed activity.