Volcanoes are something else, right? We build baking soda and papier mache models of them as kids, watch slow and steady lava flows in awe on National Geographic, and learn how quickly eruptions can destroy vibrant and significant places like Pompeii. But there are few places in the world where you can actually descend into the uncollapsed remnants of a volcano or lava tube. Luckily for us, a few of those places exist on Terceira, and we got to explore them on our last trip to the island. Algar do Carvao and Gruta do Natal – both located in the center of the island – tell different parts of the Terceira’s geological history, but both convey the power of volcanic activity to shape and reshape parts of the earth into the places we know today. We followed along with a couple of different guides to explore these remnants of Terceira’s creation, and learned that all that change might not be as far in the past as we thought.
Exploring Algar do Carvao, the greenest volcanic vent you’ll ever see
First thing’s first… it’s pronounced “Ahl-gahr doh Khar-vow” 🙂
Anyway. When you think of dropping down into the mouth of a volcano, you typically think of people in heat suits rappelling down into the fire and brimstone belly of the beast. You know what we had to do? Put up the hoods on our rain jackets and walk down an absurd number of stairs. Algar do Carvao is the only volcano in the world that you can simply walk into, without the aid of more complex equipment. And it will absolutely take your breath away.
After parking in the nearby gravel lot, we walked into the office-slash-gift shop to purchase our tickets. From there, we went through a couple of doors and into a close, concrete hallway with a gentle downward slope. After a day of hanging out with Juca from Trilhas Tours seeing the best views on the island, we couldn’t help wondering why he decided to take us to an underground attraction. Then, through another set of doors, the whole place opened up and we got it loud and clear.
Walk through that last set of doors and look up, and you’ll find yourself staring at the sky through 45 meter tube, every inch of the inside of which is carpeted with brilliant green mosses and plants, most native to the island. You’ll also find yourself constantly wiping your face, because whether or not the weather is behaving outside, it rains consistently inside the algar. The ceiling sits so close to the area’s water table that the water permeates the ground and drips down into the cave. All of this rain actually helps to fill Algar do Carvao’s seasonal underground pool during the rainy season, which is a beautiful, deep blue.
Juca taught us that the algar was formed when volcanic pressure worked upwards and eventually forced its way through to the surface – exactly what happens with most volcanoes. But Algar do Carvao is unique, in that most volcanoes collapse in on themselves once the eruption is complete because the ground has been so destabilized (you can see evidence of these collapsed volcanic craters all over Iceland, for example). Not so with this one. Lava flowed back onto itself in the lava tube, preserving the structure of the tube and the massive cavern below it. Because volcanic soil is so rich, the tube ended up looking like it was lined by a million chia pets, while the cavern became home to colorful mineral deposits and distinctive silicate stalactites. These look very different from the stalactites we saw while caving in Belize, but are absolutely stunning.
10/10, would recommend!
Venturing down into Terceira’s Gruta do Natal (or, Christmas Cave)
You know the drill by now… it’s pronounced “Groo-toe doh Nah-tahl”
Having already experienced the wonder of descending into Algar do Carvao with Juca, we weren’t certain what to expect from Gruta do Natal, one of the island’s other famous reminders of its volcanic past. While the algar looks like a huge vertical chimney lined with plants, Gruta do Natal is a more typical lava tube, in that it’s more of a cave – deep and dark, with low clearance and tricky footing. Just as we had before, we paid our admission fees at an office-slash-gift shop, but this time we also got hair nets and helmets. Huh?
We quickly realized why.
Once we left the gift shop area, we passed through a heavy door and into the low-light dampness of the gruta.
We learned that there’s a fair amount of lore spread by tour companies around how this lava tube came to be called the Christmas Cave, some more true than others. But what we know for certain is that it was opened to the public in December, and that priests on the island fashioned an altar from a conveniently-placed rock formation and, for decades, held Christmas Mass in the cave. Before that began, it was called the Horse Cave (Gruta do Cavalo), because a horse skeleton was one of the first things discovered at the site. Now, priests no longer hold mass in the cave, and visitors have been somewhat limited due to vandalism and the fact that the road running over top of the cave has begun to cause noticeable erosion. Yikes.
The cave is lit by closely-placed spotlights, which have given various mosses and small flora the perfect place to live, meaning that what should be a completely bare cave has patches of neon green near almost every light. When it catches the dew and water dripping from the ceiling, it’s actually quite lovely. Along the floor of the cave, you can easily see marks from water and lava flow. Some look like rails from a railroad, while others have formed dramatic curves and other shapes in the floors and walls. Perhaps most fascinating, you can look at the different patterns and how they layer over each other to start theorizing about which way and how the lava flowed first.
Only a few parts of this expansive gruta are open to the public at this time, as other portions are either unlit or require some serious maneuvering to get into. It’s also worth noting that even the open portions do require a little bit of negotiating to move between, and even a tight, low squeeze of a traverse at the end where my 5’6” self found minor challenges in squishing through without skinning my knees.
Should I visit Gruta do Natal or Algar do Carvao?
Volcanoes are quite literally central to Terceira’s culture and history, so visiting at least one of these famous sites is a must-do when you’re on the island. For us, while both sites have their merits, Algar do Carvao is significantly more beautiful, impressive, and accessible for most visitors. We preferred it infinitely, particularly in light of the fact that we could start to see some cracks and separations in Gruta do Natal’s ceiling that gave us pause. The only downside of the algar was the constant indoor rain, which wasn’t really a downside at all. That said, if you happen to be a volcano or cave fanatic, then by all means give Gruta do Natal a fair chance, too.
Also keep in mind that if you have small children or are movement compromised in any way, navigating either the stairs in Algar do Carvao or the tricky footing and squeezes in Gruta do Natal might prove extra challenging, so absolutely make your choice based on your own abilities and comfort level.
Pin the adventure!
A letterpress-lover’s dream: visiting the Mackenzie Printery and Newspaper Museum
