How are caves lit?

Simon Edward • July 5, 2024

Show caves across the world need to be well-lit for visitors. Discover how it's done in our accessible guide.

Back in the Stone Age, caves would be lit by fire, whether at the end of a torch or in a makeshift fire pit. Today, show caves need to be lit for two main reasons: first, to ensure visitor safety, and second, to show off the beauties inside.

But the story of cave lighting isn't a simple one. For a long time, the electric lights used would create lampenflora: lifeforms that would grow under artificial light and change the appearance of the caves. Today, cave owners circumvent this where possible with LED lighting.

In this article, we shed some light on this underappreciated aspect of cave conservation.

Why is LED lighting used?

LED lights are used for several overlapping reasons. First off, they cast a cold, strong light that shows off the stalagmites, stalactites and other rock formations with precision. They also cast enough light for visitors to find their footing and stay safe in the caves.

They're also energy efficient, partly because they don't emit any heat. At a time when energy costs are high and sustainability is a priority, this makes LED a responsible choice.

They're also low in UV and IR radiation. This means that they light up the caves without creating unwanted lampenflora.

What is lampenflora?

Lampenflora or lamp flora are lifeforms that are created in caves by permanent lighting. They include types of moss, ferns, algae and flowering plants. They're bad news – bad for cave paintings, bad for limestone and bad for existing fauna. It's not for nothing that they're known in cave circles as "green sickness" or la maladie verte.

The existence of lampenflora is an instructive example of how human activity can disrupt caves. In fact, the appearance of algae was one of the main reasons why the Lascaux cave in France had to be shut to the public.

It's a clear example of how cave owners have to strike a balance between showing off their caves and taking care to conserve them. Here at Stump Cross, it's a responsibility we take extremely seriously.

LED lights are one of the best safeguards against lampenflora, especially when placed at a distance from rock surfaces.

Filming in caves

Filming in caves is challenging – not just because of the safety concerns, but also because of the poor visibility. Filmmakers need to be resourceful when it comes to lighting their shoots.

Take the BBC's Planet Earth episode "Extremes", which included dramatic footage of the Hang Sơn Đoòng cave in Vietnam's Phong Nha-Kẻ Bàng national park. The team spent 18 hours capturing footage 200 metres below the Earth's surface.

If you want to film in the dark, you can head to your nearest electronic store and pick up a film camera. But to film in the depths of Hang Sơn Đoòng cave required a wide range of powerful lights.

The filmmakers got their results partly through the use of drones. They orchestrated a so-called "drone dance" which involved multiple drones lighting up and filming spectacular rock formations.

The length of the shoot meant that the team had to be creative in their use of power supplies. The cave floor became an "office" where the team used an electricity generator to recharge cameras and watch back footage on their laptops.

Cave photography

Caves can be perfect spots for photographs – but, like filming, cave photography requires a little extra work.

First, you'll need to experiment with your phone or camera's flash and "night mode" setting. These will be able to provide extra light where needed and bring out the details of the rock.

Secondly, you'll probably want to bring a tripod. This will allow you to make your shots extra crisp. You might also want a wide-angle lens to capture the full dimensions of the cave.

And thirdly, you'll need to handle your equipment with care. Caves are wonderful places to explore – but no one's pretending they're not damp, cold and occasionally muddy. Bring something to wipe your equipment down with and take extra care not to drop or knock your gear.

What do cavers use?

Cavers are those brave souls who like to squeeze through narrow passageways, crawl through mud and generally get up close and personal with caves.

To aid their expeditions, they carry equipment. One of the caving essentials is a light. Sometimes, these are handheld. But if the expedition requires crawling, headlamps are best.

Our underground UV cave tour

At Stump Cross Caverns, we've introduced an underground UV cave tour. This lets visitors explore the caves under UV light.

It works something like this. We give you a UV torch (and a hard hat!) You descend the 65 steps into the caverns and shine the torch onto the cave walls. Under the UV rays, they reveal beautiful secrets, including gorgeous veins of calcite.

This is possible because the calcite-riddled walls of Stump Cross are a kind of natural lamp. They absorb the UV light from your torches and then reflect it outwards.

We love seeing our visitors light up with excitement as the walls of the cave glow in the dark. It's a magical experience that you won't forget in a hurry.

Can you help Stump Cross out?

Here at Stump Cross, we take our role as custodians of the caves very seriously. This means conserving them for generations to come – and it also involves making the visitor experience as positive as possible.

The lighting at Stump Cross plays a big part. It lets you get a closer look at the colours and textures of the beautiful ancient limestone.

But our current lighting rig is over 75 years old. One of our key aims is to install state-of-the-art lighting that would protect the caves and cut energy costs.

Do you want to help us reach this target? Then please consider donating to our crowdfunder. Every little helps!

Want to discover the magic of our natural glow-in-the-dark rocks? Join us at Stump Cross Caverns after 3 PM to experience our UV cave tour. It's quick and easy to book online.

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