Mount Lachlan is the biggest volcano of New Shetland. Currently, it is dormant, but there is a lot of volcanic activity around the mountain. The mountain itself lies within tge boundaries of Nieves NP. A small mission used to be operated at the foot of the mountain, where hundreds of natives were converted to Christianity. Nowadays, it is in ruins, but it can still be visited.

The mountain is suspected to having experienced no major eruptions in the last 800 years. However, increasing volcanic activity adds to the fears that a new eruption is going to happen within the foreseeable future.