Is mountain climbing plural in English?

It depends on the situation, let me give you an example

1We linger in the lowlands because we are afraid to climb the mountains.

We linger on the ground, Because we are afraid of climbing mountains and ridges.

2.

It is difficult to climb the mountains located 3000 meters above the sea level.

It is difficult to climb the mountains located 3000 meters above the sea level. .

3 Yes, I'm afraid we can't climb the mountain today.

Yes, I'm afraid we can't climb the mountain today.

4

Take the risk and climb the mountain, you may slip like I did, but it won't stop you from reaching new heights.

Take the risk , when you climb that mountain, you may slide down like me, but that will not prevent you from climbing new ones.