등반이 · 등반을
climbing (mountains or rock)
Example
이번 주말에 친구들과 설악산 등반을 해요.
This weekend I'm climbing Seoraksan with friends.
Word parts
등 climb+반 clamber
Literally 'climbing and clambering up.'
Good to know
등산 is everyday hiking; 등반 suggests a serious climb, like Everest or rock walls.
Related words