Mauna Kea
Mauna Kea ( or , ) is a dormant volcano on the island of Hawaii. Its peak is 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 is the tallest mountain in the world measuring over . 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 due to construction of cinder cones, decentralization of its rift zones, glaciation on its peak, and weathering by the prevailing trade winds. Mauna Kea last erupted 6,000 to 4,000 years ago and is now considered dormant. The peak is only about higher than its more massive neighbor, Mauna Loa.
Teide
If measured from the ocean floor, it is at 7,500 m (24,600 ft) the highest volcano in the world base-to-peak outside of the Hawaiian Islands, and is described by UNESCO and NASA as Earth's third-tallest volcanic structure. Teide's elevation makes Tenerife the tenth highest island in the world. Teide is an active volcano: its most recent eruption occurred in 1909 from the El Chinyero vent on the northwestern Santiago rift. The United Nations Committee for Disaster Mitigation designated Teide a Decade Volcano because of its history of destructive eruptions and its proximity to several large towns, of which the closest are Garachico, Icod de los Vinos and Puerto de la Cruz. Teide, Pico Viejo and Montaña Blanca form the Central Volcanic Complex of Tenerife.