Being so used to having just about anywhere lit up for people to see their way, I hadn’t given much thought to lighting America’s largest underground natural wonders. My first trip through the Great Hall of Carlsbad Caverns was on Thanksgiving. We arrived shortly after this amazing natural wonder opened to the public. With so few people there, we were able to have parts of the trail in the Great Hall of Carlsbad Caverns to ourselves for minutes at a time.
It took a few minutes for our eyes to adjust, especially on my partner, who will have cataract surgery in a few months. The lighting was dim. In some places it seemed that once there were lights that were now burned out or off. Where we could see, we were in awe of the incredible natural growths hanging from the ceiling or rising from the ground.
Since most of the people were at home preparing for Thanksgiving food, we were able to have long conversations with the various rangers who walked through this sprawling underground wonder. One of our questions was about lighting.
The ranger told us that the lighting location was designed by an expert in the theater. There used to be much bigger and brighter lights scattered throughout the Great Hall. After a while, an unwanted consequence was noticed. Green algae began to appear on the walls. This had not happened before because the Carlsbad Caverns were completely dark before people wanted to be able to see what was inside. The first explorers came down with oil lamps or with the lamps in the helmets that the miners used. These did not produce algae growth.
To prevent green growth on the damp walls of Carlsbad Caverns, some bulbs were turned off and others dimmed. Although this reduced the growth of algae, it also decreased what can be seen. If we had thought about it, we would have brought a high intensity flashlight. This is strongly suggested on some of the guided tours where the paths are totally dark.
In the coming years, the park service will install LED lighting. These do not promote algae growth and will last longer than they are now. The park ranger explained that many more natural wonders would be seen and that the LED would allow the Carlsbad Caverns to remain in their most natural state … if you discount the fact that “natural” means total darkness.