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.
Kīlauea
Kīlauea is one of five subaerial volcanoes that make up the island of Hawaii, created by the Hawaii hotspot. The oldest volcano on the island, Kohala, is more than a million years old, and Kīlauea, the youngest, is believed to be between 300,000 and 600,000 years of age; Lōʻihi Seamount, on the island's flank, is younger and has yet to breach the surface. Thus Kilauea is the second youngest volcano in the Hawaiian–Emperor seamount chain, a chain of shield volcanoes and seamounts extending from Hawaii to the Kuril–Kamchatka Trench in Russia.