At 4392 meters tall ( 14410 feet) Mt. Rainier is the highest volcano in the cascade range. It is also the third most voluminous. Mt. Rainier is a stratovolcano. This means that it has steep sides and symmetrical cones built by alternating lava flows, ash, and cinder. Mt. Rainier's summit is built by two overlapping craters, each about a quarter-mile in diameter.