Algar do Carvão, in the middle of Terceira in the Azores, is one of the few places in the world where you can walk down inside an old volcanic vent: a tunnel and concrete steps lead 90 metres down a mossy shaft to a clear lake, past white silica stalactites. The visit takes about 30 minutes and costs €10 per person, cash or card, bought on arrival only (as of October 2026). Opening is seasonal and only in the afternoon: from October to December it opens four days a week.
Right now in Algar do Carvão
- Wed12–18°C54–64°FPartly cloudy
- Thu12–17°C53–62°FMostly clear
- Fri11–16°C52–61°FCloudy
Tickets and tours for Algar do Carvão
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What it is and why it matters
An “algar” is a vertical cave, and this one is the throat of a small volcano, Pico do Carvão, that erupted about 2,000 years ago. When the eruption ended, the magma drained back down and left the chimney open instead of plugging it, as usually happens. The mouth at the top is about 15 by 20 metres, and the shaft ends some 90 metres below in a lake of rainwater, up to 15 metres deep, which can almost dry out in dry years.
Water dripping through the rock has coated the inside with milky-white silica stalactites and stalagmites and reddish iron deposits, unusual in a lava cave. Plants grow down the walls to about 64 metres below the opening. The cave is a Natural Monument and a geosite of the Azores Geopark, and was a finalist in the Seven Natural Wonders of Portugal. It is looked after by a local caving association, Os Montanheiros, whose members tunnelled the entrance by hand at weekends in 1965–66. For the islands as a whole, see our Azores travel guide.
What you’ll see
From the ticket point a short gravel path leads to a 44-metre tunnel into the side of the cone. You come out on a platform under the open mouth, with light falling down walls hung with ferns and moss. From there stairs drop to lower landings, under vaults of silica and iron formations, to a viewpoint over the green-blue lake at the bottom. Staff from Os Montanheiros are inside to answer questions, at no extra cost.
Opening times and tickets (as of October 2026)
Os Montanheiros publish this timetable for 2026:
- 21–31 March: Tuesday, Wednesday, Friday and Saturday, 14:30–17:00.
- April and May: daily, 14:30–17:00.
- June to September: daily, 14:00–18:00.
- October to December: Tuesday, Wednesday, Friday and Saturday, 14:30–17:00.
- Closed on 1 January, Easter Sunday, 1 December, 25 December, Carnival Tuesday, 24 and 31 December.
- Tickets: €10 per person, sold only on arrival: no online booking, no advance sales, no group rates. Cash, debit and credit cards accepted (not American Express). Children under 12 with a paying adult go free, as do holders of a disability card; free and discounted entries are capped at 50 a day, and Os Montanheiros ask for requests at least 48 hours ahead.
- One queue, first come first served, with up to 150 people inside at once.
A new visitor centre is being finished next to the cave. Until then the ticket office is a temporary booth, and there is no café, shop, shelter or toilets on site. Short closures for the building works are announced on the Montanheiros website, which you should check before you go.
How hard is the visit?
All the floors are concrete, but there are a lot of steps: 114 down through two tunnels to the main landing and 338 in total if you go all the way down, and the same back up. The air is above 90% humidity and water drips constantly, so the steps can be slippery. Os Montanheiros do not recommend the visit for people with limited mobility or balance problems, claustrophobia, babies carried in arms or women in late pregnancy. Wear trainers or walking shoes and a light waterproof layer. Tripods, smoking, eating and animals are not allowed, and you must not climb walls or go down to the lake.
Getting there
The cave is near the centre of Terceira, about 12 km by road north of Angra do Heroísmo, at about 640 metres above sea level; the road is signposted. A car or taxi is the practical choice; we found no bus to the cave. Allow time for the queue in summer.
Combine it with
The official PRC10TER trail, a 6.2 km, 2 h 30 circuit, starts at the Algar do Carvão car park and crosses the central plateau to the Furnas do Enxofre fumarole field, with views to São Jorge and Pico on clear days. Gruta do Natal, a lava tube also run by Os Montanheiros, is a short drive away. Then head down to Angra do Heroísmo, a UNESCO World Heritage town, or to the lava rock pools at Biscoitos on the north coast. On Faial, the Capelinhos volcano shows what a young eruption leaves behind.
Algar do Carvão FAQ
How much does Algar do Carvão cost?
€10 per person, paid on arrival by cash or card (not American Express), as of October 2026. Children under 12 with a paying adult go free.
Do I need to book Algar do Carvão?
No, and you can’t: there is no online booking. Tickets are sold only at the cave, in one queue in order of arrival.
When is Algar do Carvão open?
Only in the afternoons and seasonally. In 2026: daily 14:00–18:00 from June to September, daily 14:30–17:00 in April and May, and Tuesday, Wednesday, Friday and Saturday 14:30–17:00 in late March and from October to December. Check the Montanheiros website for closures.
How many steps are there in Algar do Carvão?
About 338 in total, 114 of them down to the main landing. The steps are concrete but wet and can be slippery.
Is Algar do Carvão suitable for children?
For children who can manage the steps, yes, and under-12s go free with a paying adult. It is not recommended for babies carried in arms.
Sources
Researched and last reviewed by TravelerCenter on 4 October 2026. Opening times, prices, rules and the cave’s geology and history come from Os Montanheiros, the association that runs Algar do Carvão; the PRC10TER trail from the official Trails Azores site. Opening days change with the season and the visitor-centre works, so check the Montanheiros website before you go.
Data: Weather: MET Norway (CC BY 4.0) · Rates: ECB · Costs: World Bank ICP and price levels · © OpenStreetMap contributors (ODBL) · Wikidata (CC0)