Mountain climbing; mountaineering—the activity of ascending mountains, often as a sport or hobby.
週末に友達と富士山へ登山に行く予定だ。
I'm planning to go mountaineering on Mt. Fuji with friends this weekend.
登山は装備と体力の準備が非常に大切だ。
For mountain climbing, equipment and physical preparation are extremely important.
彼は若い頃から登山が趣味だ。
He has been fond of mountain climbing since his youth.