Mountain Climbing
noun, する verb
You've hopefully seen how 登る means "to climb." So, if you're climbing a mountain what is that? It's mountain climbing.
In case you're wondering what the difference is between this and 登山, they are essentially the same. The main difference is that 山登り is a little less formal, and is generally used as a standalone word, whereas 登山 can be used in compound words like 登山家 (mountaineer).
やまのぼり
The reading comes from combining 山 and 登る together to form one word, 山登り. If you know the readings of those two words you know the reading of this word too.
山登りがしゅ味なんですか？
Is mountain climbing your hobby?
ものしずかな友人と、山登りに行ってきました。
I went to climb a mountain with my quiet friend.
お互い色々あったんだけど、山登りをしながらじっくり話し合ってさ。なんと復縁することになったよ。
Both of us have been through a lot, but we had a long talk while climbing a mountain and decided to get back together.