The island of Hawai'i is the largest and tallest mountain on this planet. It rises some 33,000 feet from the deep floor of the central Pacific to its two major summits. (Mount Everest, while its summit punches almost three times higher into the sky at 29,035', has its base on the Tibetan Plateau at about 15,000'.) It has two major peaks. Mauna Loa, the one whose summit cone (rarely) and flanking cones (almost constantly) are known for spectacular lava flows is the shorter one. Mauna Kea, classified as dormant, is the taller of the two. It is also increasingly crowded with astronomical telescopes because it has excellent "seeing" as astronomers call the property of clear stable atmosphere. There are many and varied web sites about Mauna Kea. This one is a high-pointer's report. This has lots about the telescope farm. This one has web cams. And this one is about the geology.