Mauna Loa is about 60 miles wide and 30 miles long. It is the world's largest shield volcano and covers about half of the entire island of Hawaii.

Mount Mauna Loa can reach heights of 13,680 feet above sea level. The last eruption for this massive mountain was in 1984. They celebrated 25 years in March 2009. You can find more information here: http://www.soest.hawaii.edu/GG/HCV/mauna...