K2 is the world’s hardest mountain to climb.

 K2 from November to the end of February is one of the most daunting challenges in mountaineering. In an infamous section called the “Bottleneck”, climbers traverse a towering overhang of precarious glacial ice and massive, sometimes unstable, seracs. It’s the fastest route to the top, minimizing time climbing above K2’s “death zone”: the 8,000m altitude above which human life can only briefly be sustained. But too often these seracs come tumbling down, taking climbers with them.