Mauna Kea (/ˌmɔːnə ˈkeɪ. ə/ or /ˌmaʊnə ˈkeɪ. ə/, Hawaiian: [ˈmɐwnə ˈkɛjə]) is a dormant volcano on the island of Hawaii. Its peak is 4,207 m (13,802 ft) above sea level, making it the highest point in the state of Hawaii. Most of the mountain is under water, and when measured from its oceanic base, Mauna Kea becomes the tallest mountain in the world measuring over 10,000 m (33,000 ft). 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. Late volcanism has also given it a much rougher appearance than its neighboring volcanoes; contributing factors include the construction of cinder cones, the decentralization of its rift zones, the glaciation on its peak, and the weathering effects of the prevailing trade winds. Mauna Kea last erupted 6,000 to 4,000 years ago and is now considered dormant.