Mt Rainier summit crater at sunrise. Mount Rainier is a massive stratovolcano 54 miles (87 km) SE of Seattle in Washington, US. It is the most topographically prominent mountain in the contiguous US and the Cascade Volcanic Arc, with a summit of 14,411 ft (4,392 m). Mt. Rainier is one of the most dangerous volcanoes in the world, and it is on the Decade Volcano list. - and I live 30 miles away.