Long before the Sumerians pressed reeds into clay, humans may have already taken their first steps toward writing. Forty thousand years ago, in the depths of Ice Age caves, people began leaving behind ...

(CNN) — A mile and a half beneath the ocean’s surface, the seafloor seems nearly as alien as the surfaces of other planets. Deep-sea volcanic ridges, formed by the collisions of tectonic plates, ...

The underwater caves of the Yucatán Peninsula are a window to the distant past. Through two million years and over multiple glaciation cycles, these caves have been transformed. When the sea level was ...

Hidden beneath the water’s surface, these caves offer a unique beauty that few have the chance to witness. Imagine swimming in crystal-clear waters, surrounded by dramatic rock formations, and ...

MT. RAINIER NATIONAL PARK, Wash. - A hike into ice caves near Mt. Rainier turned into an incredible experience like no other when the ice became awash in brilliant colors. "I could not believe my eyes ...

VERLOT, Wash. (AP) — The U.S. Forest Service says it will reopen the trail leading to the Big Four Ice Caves this spring with new warning signs. The trail to the hiking destination closed after July 6 ...

Editor’s note: A version of this story appeared in CNN’s Wonder Theory science newsletter. To get it in your inbox, sign up for free here. A mile and a half beneath the ocean’s surface, the seafloor ...