Mauna Kea is a dormant volcano on the island of Hawaii. Its peak is the highest point in the state of Hawaii making the island of Hawaii the second highest island in the world. Most of the mountain is underwater; when measured from its oceanic base, Mauna Kea is over 10,000 m (33,000 ft) tall and is the tallest mountain on Earth.
Mauna Kea is about a million years old and has thus passed the most active shield stage of life hundreds of thousands of years ago. In its current post-shield state, its lava is more viscous, resulting in a steeper profile.