Algar do Carvão

Coal Pit - Gruta do Algar do Carvão

Useful Information

Location:	Porto Judeu, 9700-000 Angra do Heroísmo. At the Terra Brava, center of Terceira island. Monumento Natural do Algar do Carvão. From EN 5-2A (38.7281442, -27.2158972)
Open:	JAN to MAR Tue, Wed, Fri, Sat 14:30-17. APR to MAY daily 14:30-17. JUN to SEP daily 14-18. OCT to DEC Tue, Wed, Fri, Sat 14:30-17. Closed 01-JAN, Carnival, Easter, 01-DEC, 24-DEC, 25-DEC, 31-DEC. [2024]
Fee:	Adults EUR 10, Children (0-11) free. Combo Ticket Algar do Carvão + Gruta do Natal: Adults EUR 15. [2024]
Classification:	lava cave
Light:	Incandescent Electric Light System
Dimension:	L=100 m, VR=90 m, H=90 %.
Guided tours:	D=30 min, St=338. V=22,000/a [2009].
Photography:	allowed, no tripod
Accessibility:	no
Bibliography:	Paulo Barcelos (2010): Algara do Carvão SIARAM Sentir e Interpretar o Ambiente dos Açores, Horta (Azores), Portugal: SRAM Secretaria Regional do Ambiente e do Mar pdf
Address:	Os Montanheiros, Rua da Rocha 8, 9700-169 Angra do Heroísmo, Tel: +351-295-212-992, Cell: +351-961-362215, Fax: +351-295-216465. E-mail:
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then. Please check rates and details directly with the companies in question if you need more recent info.

History

26-JAN-1893	discovered.
1934	exploration and cave map by Didier Couto.
18-AUG-1963	exploration with a winch with a nylon line.
1968	opened as a show cave.
2004	show cave reopened after cave entrance building and interior were renovated by the mountaineering club Os Montanheiros.

Description

Algar do Carvão is a huge, about 100 m long lava cave, which is the remains of a volcanic eruption of the Terra Brava (707 m asl) named do Pico Alto. It happend 2148±115 BP, this was determined by dating the fossils which were found associated with the lava flow. Unlike most other lava caves it is not a lava tube, which is the result of a calm downhill flow of lava. This is the vent where the lava erupted and is thus more like a shaft (algar) than a cave. The name Carvão means coal pit in English, and was given to the cave because of the cave walls of dark black lava, there is no coal found on this island. There is another cave with a similar name, called Showcave Grouta do Carvão on Region São Miguel Island. The explanation is simple, most of the caves on the islands are lava tubes, and lava very often has this dark black colour. As a result there are various "Coal Pits".

Quite astonishing is the fact that this volcanic cave contains stalactites and stalagmites. They were formed by silica, dissolved from the lava, not by calcite as in karst caves. This is really exceptional, and the result of a special chemistry of the lava.

The cave is entered through a narrow tunnel with 36 steps. Once in the main chamber it actually goes down or back up all the time, the cave has almost no horizontal part, its more like a steep shaft which forks into two branches. The end of the tour is a subterranean lake, formed by rain water. To reach this lowest point, there are 338 steps in total. Depending on the season and the amount of rain water, the lake can be up to 15 m deep. The whole cave is spacious, the passage is up to 45 m in diameter. The access to the lake is currently closed [2024].

Due to the vertical nature of this cave, it was not easily accessible, from the natural entrance it is necessary to abseil down a shaft. This was first done on 26-JAN-1893, with the use of a simple rope by Cândido Corvelo and Luis Sequeira. So this is the official discovery date. It took until 1934 until the next explorer descended, Didier Couto. He made a drawing of the cave which was only based on his visual observations, he did no survey, but nevertheless his map turned out to be quite accurate. The next attempt was made on 18-AUG-1963, the cavers organized a winch with a nylon line, first they used a chair, later a harness. After the exploration, the cave was developed with an artificial access tunnel, which avoided the vertical drop of the entrance. After only five years, it was opened a show cave. The site was open to the public during the late 20th century, on weekdays for organized tours, but closed on weekends and during holidays. But rather early the non-profit organisation Os Montanheiros also organized cave tours. Finally, they took over and started a complete renovation of cave entrance building and interior and reopened the show cave in 2004. The cave and the surrounding area were declared a natural monument after their initiative.

Close to the cave are the Furnas do Enxofre, sulfuric springs, well worth a visit. The best time for a visit is early in the morning, as the area gets very hot when the sun shines on the black rocks. At the cave is the trailhead of a trail which goes around the Terra Brava. It is said to be probably the most beautiful walk on Terceira, but be careful with bulls, which are bred for bullfights. The walk takes four hours.