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Mónica Jardim

Algar do Carvão: Inside a Volcano in the Azores

Blog » Travel » Algar do Carvão: Inside a Volcano in the Azores

Imagine that you could visit the inside of a volcano. ‘Impossible!’ you might think. Well, in the Azores, everything is possible. Indeed, Algar do Carvão in Terceira island provides a once-in-a-lifetime experience with its open crater. 

In this post, we will learn everything you need to know about the fascinating cave. Lace your walking shoes and let’s go on this unique adventure!

What is Algar do Carvão

Algar do Carvão is a 90-meter-deep volcanic chimney in the central group of islands in the Azores archipelago. It was formed about 3,200 years ago due to several eruptions. 

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Nowadays, Algar do Carvão is a touristic highlight not to be missed when visiting Terceira. All year round, many travelers from all over the world venture inside the earth’s depths from this cave recognized as a Regional Natural Monument.

Geology & Volcanology

The cave was created after the magma drained from the chimney flowing back into the chamber. The first big eruption leading to Algar do Carvão is known as Pico Alto. It occurred North of the Guilherme Moniz volcanic complex and spread lava far away.

But later on, a basaltic eruption created the strombolian volcano Pico do Carvão and the current Algar as we know it today, including the lake area.

🛈 Did you know | Researchers found a fossil and estimated it to be approximately 2,148 years old. 
Mónica Jardim | It's impossible not to be amazed by being inside a volcano, literally. Algar do Carvão
Mónica Jardim | It’s impossible not to be amazed by being inside a volcano, literally

Algar do Carvão is a true geological wonder. Thanks to its uniqueness, it gained international scientific fame and is now a significant Geosite of the Azores Geopark.

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History & Geography

In 1893, the first explorers Cândido Corvelo and José Luís Sequeira entered the cave. Then, in 1934, Didier Couto was the one to create the profile of Algar do Carvão. At that time, the only way to explore it was to use a rope.

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Organized descents to the cave only began in 1963, thanks to the association still in charge of this place: Os Montanheiros (the Mountaineers). This group of local enthusiasts revealed the beauty of Algar do Carvão to the world and began construction to make access easier and fully explore the cave.

As you would need a whole day to visit the cave at that time, they decided to open a 44-meter-long tunnel in 1966 and build the current 300-meter-long staircase in 1977.

This natural monument is located in the central area of Terceira, inside the great volcanoes that formed the island. The total area of Algar do Carvão is 40,5 acres. 

Bruno Ázera | A fantastic photo that details the shape of this volcanic chimney. Algar do Carvão
Bruno Ázera | A fantastic photo that details the shape of this volcanic chimney

Culture & Festivities 

Representing a great natural stage perfect for echoing music, Algar do Carvão already hosted several live concerts by popular national bands. For instance, in 2017, the group Fado Preto Fado Branco performed beautiful traditional Fado songs.

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Algar do Carvão hasn’t only hosted musical but also cultural and religious events like the celebration of the Eucharist. This place also attracts many TV reporters for documentaries.

Fauna & Flora

Algar do Carvão looks a bit hostile for any life to be possible there, but you can actually see many birds if you look closely. Mostly at night, it is possible to spot sparrows, common blackbirds, and chaffinches. From time to time you can also see rabbits that fell off the crater edge, and of course, many arthropods (insects).

In terms of flora, the cave shows an abundance of vegetation in the green crater walls. Between the plants, you can find Macaronesian holly, Erica azorica, Azores laurel, Azores blueberry, and ferns. There is also ivy, carex, brownwort, and many types of mosses and liverworts. Deeper down, only some ferns, Bryophyta, and diatoms are surviving the darkness.

Alvaro RP | The top of the volcano chimney is now fully covered by flora. Algar do Carvão
Alvaro RP | The top of the volcano chimney is now fully covered by flora
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What to do at Algar do Carvão

You can visit Algar do Carvão all year round for about 30 minutes of exploration. It is definitely something to add to your must-sees on Terceira island. Nowadays, there is light and an indicated path for a safe visit. 

There is a maximum number of 150 persons at a time inside the cave but there is no need to book in advance, you can simply go to the entrance and buy your ticket there.

Enter the cave

Alvaro RP | Tourists walking around the Algar do Carvão
Alvaro RP | Tourists walking around the Algar do Carvão

When you enter the visitor center, you will go down the stairs and cross the tunnel to the inside of Algar do Carvão. There are 338 steps in total connecting the different balconies. The floor is concrete so it is an easy walk. 

The chimney offers the only natural light inside the cave. It is the perfect spot to take beautiful pictures of the famous crater covered by vegetation. 

Explore the inside of Algar do Carvão

Andreia Azevedo | View from the top of the volcano over the interior

Welcome to the underground wonderland! Inside Algar do Carvão, it is like walking on another planet. Nothing looks similar to our world. There are impressive stalactites, which are evidence of the eruption that gave birth to the cave.

If you continue straight you will find the ‘Boca dos Enganos’, a dead end. There are also some restricted access areas for research and preservation purposes.

Look around and find the magnificent whitish walls with some red veins. The rocks are rich in ferric and silica minerals, and you can also see some basalt layers.

Go to the lake

jwhatx | Photo of the lake in the bottom of Algar do Carvão
jwhatx | Photo of the lake in the bottom of Algar do Carvão

At the bottom of the 90-meter-deep chimney lies a lake with crystal clear waters. The lake is mostly filled with rainwater, so the depth varies according to the seasons. It can go up to 15 meters deep, 400 square meters in diameter. During years with little rain, the lake can be almost dry.

Researchers once found a perfectly preserved fossil of a seabird covered in silica at the bottom of the lake. In Algar do Carvão, the lake is beautiful. But you can only see it from a distance. Note that it is forbidden to swim in the lake.

Back to the visitor center

After visiting all the parts of the cave, now it is time to go back to the visitor center. Look around one last time and climb up the 80 meters of elevation. 

The center is quite small, but there is currently a construction project for a new center with a 1,5 million euros budget. It will be much bigger – 900 square meters – with a focus on educational exhibitions to raise awareness for this important natural treasure.

Andreia Azevedo

Best time to visit Algar do Carvão

You can visit the Algar do Carvão every month of the year. But there are some significant differences you need to know in order to choose the right time to go and explore the cave.

The Weather in the Azores in January
The Weather in the Azores in February
The Weather in the Azores in March
The Weather in the Azores in April
The Weather in the Azores in May

Best season

In the lower season, the cave is open only on some days of the week. If you are coming only a couple of days to Terceira, make sure Algar do Carvão is open during your stay (see the operating hours section below). 

So, for more flexibility, summer is the best season. But in the summertime, the cave can get a bit crowded as there are more tourists than in the other seasons.

Best time of the day

If you want to have the place to yourself or with a few people, the best thing to do is to go around the opening hour. How amazing can it be to stroll inside a volcano on your own?

For the most light, around 12 pm is probably your best bet. However, when the sun goes lower the golden light creates a unique atmosphere. 

Plan your visit to Algar do Carvão

In this part, we will see useful information in order to spend a good time and enjoy every bit of Algar do Carvão. Keep on reading for the best tips.

How to get to Algar do Carvão

The volcanic cave of Algar do Carvão, at 640m of altitude, is in the middle of Terceira island. It belongs to Porto Judeu parish, 12km from Angra do Heroísmo city northwards. 

The access is relatively easy and well indicated. However, you need a car to get there as there is no public transportation that can take you to Algar do Carvão. So, your best bet is to rent a car, go on a guided tour or take a cab.

If you are traveling with kids or elder people

The visit to Algar do Carvão is not recommended for babies or lap children, according to their official website. Also, they don’t recommend pregnant women at an advanced stage of pregnancy to go into the cave.

If you are traveling with someone with physical limitations, you should notify reception when you arrive, before entering the cave.

What to bring

As the floor inside Algar do Carvão is always wet, using suitable shoes like walking boots or sneakers is highly recommended, as well as a raincoat. 

🛈 Did you know | The average temperature inside the cave is 12 to 13ºC, so it is quite cold. Bring appropriate clothing to keep you warm. 

Pricing & Operating Hours of Algar do Carvão

Sereiazores | A detailed photo of one of the fauna species you will find in Algar do Carvão
Sereiazores | A detailed photo of one of the fauna species you will find in Algar do Carvão

Ticket prices for Algar do Carvão in 2022:

  • Adults (from 12 years old) – 8 euros
  • Children – free (must be accompanied by an adult).
  • European Youth Card holders – 6 euros. 

From January 1st, 2023, the price will change due to the rise of the fuel price as the electricity inside the cave works with generators that run on fuel. 

  • Adults – 10 euros
  • European Youth Card holders – 8 euros

It is important to note that there are no bookings. Algar do Carvão works on a first come first served system.

Opening times for Algar do Carvão in 2022:

  • January 1st  – March 31st: Tuesdays, Wednesdays, Fridays, and Saturdays – 2:30 pm – 5:00 pm 
  • April 1st – May 31st: every day – 2:30pm – 5:30pm
  • June 1st – September 30th:  every day –  2:00pm – 6:00pm
  • October 1st until December 31st: Tuesday, Wednesdays, Fridays, and Saturdays – 2:30 pm – 5:00 pm 

Note that the cave is closed on January 1, Carnival, and December 1st, 24, 25, and 31. The hours are limited in order to preserve the ecosystem as much as possible. This way, the number of hours with artificial light affecting the fauna and flora, as well as the geological formations inside, can be reduced.

More information is on the official website.

Where to eat near the Algar do Carvão

If you need a place to eat near Algar do Carvão, click here. In this link, you will find the Top 10 restaurants on Tripadvisor.

Useful Tools & Apps

In order to check the weather forecast for the next few days, use windy or windguru, they are the most accurate sites. However, here in the Azores, you will learn that the weather changes very quickly.

Where to Stay near Algar do Carvão

In order to make it easier for you, we already filtered the search on:

Pro Tips for Algar do Carvão

At the reception of Algar do Carvão, make sure you have some cash as the mobile network is unstable and can affect payments by card.

A very important thing to remember is that the collection of geological samples is forbidden. Take nothing but pictures. Speaking about photos, tripods are not allowed inside the cave.

What to do around Algar do Carvão

After visiting the cave, let’s see what is around to keep a great day going on Terceira island.

Visit Gruta do Natal

Pulga no Passaporte | As in Algar do Carvão, you will find many flora species inside the wonderful Gruta do Natal
Pulga no Passaporte | As in Algar do Carvão, you will find many flora species inside the wonderful Gruta do Natal

When visiting Algar do Carvão, it is possible to buy a combo ticket to also explore Gruta do Natal (“Christmas Cave” if translated literally). In 2022, the double ticket costs 12 euros per adult, from January 1st, 2023 it will be 15 euros, for the 2 caves. 

Each cave is completely different and both are worth a visit. While Gruta do Natal is smaller, the visit is a bit longer. In fact, you will have a briefing at the reception and will be given a helmet to enter the cave.

Inside, there are two staircases and you can walk on the original floor, not concrete ground. The access is a bit more difficult but it provides a great experience closer to nature.

Walk around Angra do Heroísmo 

Angra do Heroísmo is the largest city in Terceira with 10,000 inhabitants. It is characterized by the famous green peninsula of monte Brasil right behind the city, and also by its lovely narrow streets and colorful houses. 

Angra was classified as World Heritage by UNESCO in 1983. It is so nice to stroll around and learn more about its rich history through monuments and museums.

Among the museums, if you wish to learn more about the geology and volcanology of the island, don’t forget to visit the Volcanospeleological Museum, owned by the Montanheiros association.

Relax at Biscoitos Natural Pools

João Santos | Amazing drone shot over the Biscoitos natural pools. Algar do Carvão
João Santos | Amazing drone shot over the Biscoitos natural pools

The natural pools at Biscoitos, North coast of Terceira island, are the perfect place to lay your towel and enjoy the sun. Locals and travelers just love it there.

There are several pools to swim, snorkel, and even some spots to jump from the volcanic rocks. The crystal clear water is good to swim in all year round, the warmer months being August and September.

Stop at Serra do Cume viewpoint

Bruno Ázera | The viewpoint of Serra do Cume is one of the most famous photographic spots in Terceira island
Bruno Ázera | The viewpoint of Serra do Cume is one of the most famous photographic spots in Terceira island

Serra do Cume is probably the most famous viewpoint in Terceira, and one of the most famous in the whole Azores archipelago.

From there, you can see a good part of the island and the ocean. Don’t forget to take pictures from the wooden platform with the view of the green fields, typical of the Azores.


Complementary Info

Cultural Agenda in Terceira Island

Terceira island has a lot of cultural events to offer year-round. You can check the complete upcoming events list on the following link. View the Agenda!

How to get to Terceira island

There are many different ways that travelers can get to Terceira island by plane. The main entrance points are via Lisbon, Oporto (on the mainland), and Ponta Delgada (São Miguel island) but there are already many direct routes.

The best way to find a flight that works for you is to use a flight search engine like eDreams or Skyscanner. As you may already know, these websites allow you to compare prices and schedules from multiple airlines all in one place.

Once you’ve found a flight that works for you, all you need to do is book it! And then, in just a few short hours, you’ll be on your way to one of the most beautiful archipelagos in the world.


Algar do Carvão, a protected reserve since 1987, receives thousands of visitors every year, from all around the globe. It actually is the most visited cave in the Azores with 60,000 entries in 2019.

If this magical place was not on your list of places to visit in Terceira, you definitely need to add it now.

Image Gallery


Associação os Montanheiros – Algar do Carvão

Explore Terceira – Algar do Carvão

By Açores – Gruta do Algar do Carvão – Ilha Terceira

National Geographic Portugal – Algar do carvão, viagem às entranhas da Terra na ilha Terceira

Férias em Portugal – Algar do Carvão, Ilha Terceira

Quilómetros que contam – Ilha Terceira: em torno do Algar do Carvão

Melissa Masvaleix

Nature lover and adventure seeker, Mélissa is a French girl who landed in the Azores 3 years ago and never let go of this paradise in the Atlantic. She particularly enjoys the tranquility of the islands contrasting with the infinite outdoor experience possibilities.

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