@luoshimin
Why does no one explore mountain crevasses? I would imagine climbing into & out of one can't be as difficult as the climb to get there. Who knows what could be frozen inside the crevass?
It is easy to climb in and out of open narrow crevasses- This image is from a mountaineering class on the Hotlum Glacier on Mt. Shasta in California in 1985. The top guy is rappelling down into the crevasse, the bottom guy is my brother climbing out.