Mt. Rainier and Mt. Adams are not quite twin peaks, but their profiles and sizes are very similar to one another. Both mountains are of volcanic origin and neither has seen a large eruption in hundreds of years. Mt. Rainier is considered one of the most dangerous volcanoes and is overdue for increased activity. With the increasing growth and development in the lowlands of the Puget Sound region, many people are now at risk from the potential for lahars and mudflows that might accompany a large eruption.