Volcanoes are also prodigious land builders - they have created the Hawaiian Island chain. Kīlauea and Mauna Loa, two of the world's most active volcanoes, are still adding to the island of Hawaiʻi. Mauna Loa is the most massive mountain on Earth occupying an estimated volume of 19,999 cubic miles. The current summit of Mauna Loa stands about 56,000 feet (17,000 m) above the depressed sea floor. This is more than 27,000 feet (8,230 m) higher than Mount Everest. In contrast to the explosive continental volcanoes, the more fluid and less gaseous eruptions of Kīlauea and Mauna Loa produce fiery fountains and rivers of molden lava. These flows, added layer upon layer, produced a barren volcanic landscape that served as a fountain for life. Hundreds of species of plants and animals found their way across the vast Pacific on wind, water, and the wings of birds. A few survived, adapted, and prospered during this time of isolation. The arrival of humans - first Polynesians, then Europeans - and the plants and animals they brought with them drastically altered this evolutionary showcase, this grand natural experiment.