"Snaking, cracking, shimmering a brilliant blue in places and covered by mystical frost in others, the Mer de Glace displays nature in all its powerful glory. France’s longest glacier stretches for 4.3miles and is over 650 feet deep. Quite literally a sea of ice, it continues to move under its own weight; its surfaces break up, crevasses appear, and pointed columns of ice known as seracs burst from the surface. Though this glacier continues to amaze,it’s slowly being decimated byclimate change—in 1988, you only had toclimb down three steps to reach the ice grotto, which is carved out every spring; now, the ice has receded so much that you have to tackle 430 steps."