Hawaii's Mountainous Oahu Will Someday Be Flat Check back in about 2 million years By John Johnson, Newser Staff Posted Dec 22, 2012 11:13 AM CST 26 comments Comments A hiker looks out over Kailua Bay on the Hawaiian island of Oahu. (AP Photo/Carolyn Kaster) (Newser) – Hawaii's island of Oahu is renowned for its mountainous vistas, but someday it's going to be flat as a pancake, or at least as flat as Midway. So say researchers from Brigham Young University in a new study, reports UPI. The big factor isn't what you might expect, namely external erosion. Rather, the island's own groundwater is slowly dissolving the mountains. The weird part, explains PlanetSave, is that Oahu's elevation is actually going to keep growing for 1.5 million years because of how it's being shifted by tectonic plates. But after that, the slow descent begins.