Guadalupe Mountains is adjacent to, and just over the New Mexico border, from Carlsbad Caverns National Park.
It is one of the lesser known and visited parks in the National Parks System. Even though it is adjacent to Carlsbad Caverns National Park, it gets less than half the visitors.
Guadalupe Mountains is the remains of an ancient reef which once was near the shore of ancient sea. Carlsbad Caverns is also part of the ancient reef and the caves are a result of water dissolving the limestone.
Mostly a wilderness area, Guadalupe Mountains aren’t going to attract the same type of visitors that go to other national parks. I’d highly recommend visiting if you are going to Carlsbad Caverns, as it is right there. Visiting the park as a destination by itself is something that few people will probably do.
I think it would probably be a good idea to merge the parks into one single unit.