Grand Avenue Tour at Mammoth Cave National Park, Kentucky: Inside the Longest Cave In The World

Last week, Henri and I took the Grand Avenue Tour at Mammoth Cave National Park, KY. Mammoth Cave National Park hosts the longest cave system in the world by far, with 400 miles of trails and passages. With such a huge underworld to discover, it is not a surprise if dozens of tours are offered, from very short & easy to very long & strenuous. Here is a review with pictures of the Grand Avenue Tour.

Mammoth Cave Grand Avenue Tour, Passage

The Tours at Mammoth Cave National Park

We took some time in order to compare all the tours available.

All tours are guided by a Park Ranger. There is no way to visit the cave independently, maybe unless you are an experienced caver working for National Geographic or don’t mind seeing only the cave entrance and a few steps during the $5 self-guided tour.

Tours are available or not depending on the season, so we had to check what was available last week. Basically, the shortest tours are portions of the longest tours, they are also the easiest. Some tours have a larger maximum capacity than others. Grand Avenue Tour seemed to be one of the tours allowing visitors to see the most of the cave: 4 miles, 4 hours, “strenuous”, $26. We decided to go for this one after hesitating a lot with the Historic Tour.

This map (which was hard to find, it is only visible at a booth inside the Visitor Center) shows where each tour goes. The dark blue trail on the second picture represents the portions of the cave seen on the Grand Avenue Tour. As you can see, one of the most famous sights at Mammoth Cave, the Bottomless pit, is not visible on the Grand Avenue Tour. The trade-off is that you see portions of the cave that are far less busy and not visited in other tours.

Mammoth Cave Tours Map (1)Mammoth Cave Tours Map (2)

Grand Avenue Tour at Mammoth Cave: What to Expect

We started off at 9 am sharp at our meeting point behind the Visitor Center. There were about 70 other visitors, which is not as bad as it sounds. The tour started with a quick safety introduction from our Park Ranger, who had a very strong Kentucky accent, but a loud voice that was very welcomed for such a large group. Many things are forbidden on the tour, such as:

  • Touching anything, and they really mean anything, even the walls, the stones
  • Bringing a souvenir home from the cave
  • Flash photography (it was still allowed until four years ago, to our surprise)
  • Eating

A 5-minute bus ride then took us to the entrance of the cave.

Henri walking the Grand Avenue tour, Mammoth Cave

The entrance  doesn’t really look like what you could have in mind, it’s basically just a door with multiple steps to take in order to get to 150 feet underground. After a couple other reminders from the ranger to not touch anything inside the cave, we walked down for about five minutes until we reached a first large corridor.

Mammoth Cave, Grand avenue Tour

When you see the cave for the first time, you will know you’re visiting a special place. It’s absolutely gorgeous, staggering. Some might be disappointed because it’s not immediately a typical cave with stalactites and stalagmites, you’ll have to wait for the end of the tour to see that. Mammoth Cave is mostly a dry cave. But the colors, the size, the light… it’s truly fantastic. I’ve seen a few caves in Europe, but nothing that compares to such beauty.

Mammoth Cave Grand Tour

The trail is made of sand, which was probably brought from outside as it’s the only thing that doesn’t look like limestone. It’s really easy to walk. The first mile is mostly flat, so the pace of the group was quite fast.

Narrow Passage, Mammoth Cave

During the first couple stops, the ranger told us a lot about the discovery of the cave and the creation of the Mammoth Cave National Park, with many anecdotes and “jokes” referring to popular American culture. If you’re not American it might be a bit difficult for you to understand, but since most of the visitors are locals, it’s fair of course. It got me a little impatient at some point because I was more interested in learning a bit about geology than listening to a joke involving the Flintstones or a Kentucky mother-in-law. These Europeans, far too serious.

Mammoth Cave, Grand Avenue Tour, Limestone

The trail then goes into some very narrow passages where you have to bend your shoulders and watch your head a lot. I was staying at the end of the trail with the park ranger closing the group, so I could take some photographs.

Mammoth Cave GraffitiMammoth Cave Narrow Path

My curiosity for geology was satisfied during the third stop, about halfway in the tour. At this point, the trail started to be kind of steep. The ranger gave a Geology 101, and explained how the cave was created. Spoiler: it involves billions of years and a lot of water.

Mammoth Cave Grand Avenue Tour, ShadowsMammoth Cave, Limestone formationMammoth Cave Geology 101

Not long after that third stop, there was a first bathroom stop. Yes, they did build a restroom inside a cave. You know my fascination for public restroom availability in the U.S., it is truly amazing. And you know what? There is a SECOND bathroom stop near the end of the trail. Truly amazing. You are not allowed to eat in the cave, but you can pee. Basically the opposite of how it would be in France.

Mammoth Cave Limestone Roof

The second half of the trail (miles 2 to 4) was far more difficult as it became a lot steeper, and we frequently had to hold a banister to get up and down, but it’s also the most dramatic in terms of landscape. I was sweating but I would say that it’s just regular exercise if you’ve successfully completed an average 2-hour mountain hike in the past. Only one person in the group felt sort of dizzy at the end of the tour.

Reliefs, Mammoth Cave

Near the end of the trail, the rangers completely turned off the lights while we were all seating inside a gigantic canyon, and everyone had to remain silent for a few seconds. It was a sensation of complete darkness and silence I had only experienced before in the Lascaux Caves, in Dordogne, as they do something similar during the tour there. It’s not scary because you know you’re safe, but if I had to be in this situation alone in the cave my mind would go crazy (have you seen The Descent?)

Shapes in Dim light mammoth cave

The very last part of the tour is the “Frozen Niagara” part. This part of the cave is “wet” and this is where you can see stalactites and stalagmites, both inside a pit and a corridor. They are truly photogenic.

Mammoth Cave Frozen Niagara StalactitesMammoth Cave, Frozen Niagara Stalactites

Photographing Mammoth cave

Here is the context: the cave is all lighten up but you can’t use a tripod, stones as a tripod, flash. Intuitively —I unfortunately did not study much about cave photography before descending— I used a large aperture and high ISO. I wasted a lot of energy trying to photograph areas that were too dark, and most of my pictures ended up blurry, of course. Sometimes, they turned out okay but the colors are not very realistic.

Limestone Wall inside Mammoth Cave

Still, I had a lot of fun and got a few decent shots that I wanted to save for this post. The lightning in the cave is truly spectacular and makes it easy for a beginner like me to play around. If you manage to put people on the picture, I think it looks even better. I also enjoyed trying out close-ups of the limestone layers, in this one below I see a Picasso painting face for example.

The Broken Picasso, Mammoth CaveMammoth Cave Lightning

A few tips on how to behave if you want to take photographs on this tour:

  • You won’t get much done with an iPhone, you need a DSLR / something professional.
  • Bring your hood in order to protect the lens, you’re likely to hit a few stones
  • Stay in the back with the second park ranger, but try to not be annoying by loosing the group
  • If you’re tempted to use something in the cave as a tripod, don’t even think about it, the ranger will yell at you. I tried to use a plug device that was on the path, as I thought it did not qualify as a “stone”. But it did qualify as a cave stone. You can use the banisters for support.

the hole mammoth cave

If you take one of the tours at Mammoth Cave I advise you to spend at least one night there. We camped at the Houchin Ferry Campground, a primitive campsite (water and porta-potty only) about 25-minute drive from the Visitor Center ($12/night). Happy Caving!

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