Piton de la Fournaise

The first recorded ascent to the volcano took place on 21 September 1751. This expedition was led by the knight Andoche Dolnet de Palmaroux, and per the scarce notes from this expedition probably only one summit crater existed at that time. The first scientific expeditions took place in 1771 and 1772 led by Philibert Commerson (1727-1773) and Lislet Geoffroy (1755-1836), who was only 16 years old at the time.

Nevertheless, it was only during the 1801 expedition by Jean-Baptiste Bory de Saint-Vincent (1778-1846) that the volcano was thoroughly researched. They started the ascent on 25 October at Piton Sainte-Rose, going through Bois-Blanc along the floor of Rempart de Bois-Blanc to Trou Caron and the foot of the Crac piton where they set up their camp and started exploring the Osmondes plains. On 28 October, Bory climbed the main dome and reached the summit between the two main craters at one o'clock in the afternoon. At the time he reached the summit, the crater now known as Dolomieu began erupting.

Almost 300 eruptions have been recorded since 1650, though the real number is likely larger, given that records of eruptions have been taken systematically only since the mid-20th century. Eruptions have usually taken place in the main craters of the central dome or elsewhere in the inner caldera. A few times eruptions have taken place elsewhere, for instance in 1977 and 1986 causing destruction in nearby villages.

The volcano was notably inactive in the 1990s, ended by a huge eruption in March 1998 that lasted 196 days. Since then there have been several eruptions (of varying intensity) every year, with major ones having taken place in 2004, 2007 and 2014. During the April 2007 eruption, the Dolomieu crater cracked open and the magma chamber with a century's worth of lava emptied down the mountainside and into the ocean, making for a massive spectacle. With two to three eruptions every year, the likelihood of seeing an eruption is higher than at most other volcanoes in the world, though you will still need a bit of luck to be there at the right time. The last eruption began on 14 July 2017 (the French National Day) going on until late August.

The outer caldera is named Rempart and is about 5,000 years old. The biggest and physically largest attraction here is the Plain des Sables, a black plain of volcanic rock that the road to the volcano crosses.

Inside it, delimited by cliffs ranging from 100 to 400 m in height, is the inner caldera, Enclose Fouqué. This flat plain, about 2,200 m above sea level, is almost completely devoid of vegetation and is dominated by volcanic rock and ashes from recent eruptions. It is shaped like a horseshoe with an opening to the east, and spans some 13 km from east to west and 9 km from north to south. In the middle of this moon landscape is the dome of the volcano, rising 400 m above the caldera floor and forming the summit of the volcano. The dome has a diameter of about 3 km and comprises two craters, Bory and Dolomieu:

• Bory, the smaller of the craters, is situated to the west and is about 350 m long and 200 m wide. It already existed when the island was first colonized, and was named after the naturalist Jean-Baptiste Bory de Saint-Vincent who led an expedition to the crater in 1801, and made the first maps and scientific observations of the volcano.
• The eastern crater, Dolomieu, is more active and considerably larger; about 1,000 m long and 700 m wide. It emerged in 1791, after a collapse of a magma chamber summit, and collapsed even more in a 2007 eruption. Bory named the crater after the geologist Déodat Gratet de Dolomieu.

The volcano forms part of the larger Piton de la Fournaise massif, itself a shield volcano covering the entire island including the Piton des Neiges (Réunion's highest summit and a dormant volcano). The oldest rocks of this massif are 530,000 years old, older than the island itself in its current form. Located at a hotspot, Réunion was created through volcano eruptions over the course of 2-3 million years, and as such it has "risen out of the sea" like Hawaii.

Piton de la Fournaise attained its current form after an explosive eruption some 4,700 years ago, when a large area collapsed forming what now is known as the inner caldera. Traces from this explosive event, known as Bellecombe ashes, can be found up to 10 km from the volcano. After this, subsequent eruptions have built up the dome in the middle of the inner caldera.

Most eruptions begin with lava fissures several hundred meters long emerging, from which lava flows evenly like waterfalls. Minutes to hours later the eruption starts concentrating in a few exit points, where lava is shot out at a more uneven pace. Lava that is propelled out with less force often spreads around a large area, but lava that is ejected high up in the air congeals and falls down forming cones known as pitons. Eruptions may involve multiple cycles of fissures and exit points.

The fact that the lava is runny makes the eruptions (compared to volcanic eruptions around the world in general) less violent and hence safer to watch, and they are indeed a popular attraction with locals and visitors alike. Also, ash clouds are rare, though the volcano sometimes creates Pele's hair (see below).

This type of volcanism, hotspot volcanism, creates several different types of lava. Their names come from Hawaiian:

• Pāhoehoe lava (Lave cordée) is the hottest type (1,100-1,200°C), and hence runny and with an almost glossy surface. Due to this, the name translates to "smooth flow". When the lava has cooled down, it gets a glitzy, satin-like surface.
• ʻAʻā lava (Lave en gratons) is cooler (around 1,000°C), less runny, and flows slower. This type of lava often catches loose rocks along the way, and therefore looks like a plowed field. This name of the lava mimics the exclamation of someone walking barefoot over the cooled lava (with sharp edges).
• Pele's hair (Cheveux de Pélé) is named after the Hawaiian volcano goddess Pelé and is volcanic glass fiber that looks like hair and is certainly sharp enough to penetrate skin. It is ejected through lava fountains or lava cascades and can be carried by the wind for several kilometers.
• Pele's tears (Larme de Pélé) are lava drops that have been ejected in the air and congealed into chunks of volcanic glass.

Piton de la Fournaise and the surrounding area are continuously remodelled by the eruptions, and this naturally also goes for the flora. But as soon as the lava has completely cooled down, plants start growing on the slopes again. The lichens are the first to emerge, followed by ferns, shrubs and trees. The growth is slower at higher altitudes with rougher conditions, but in the valley a forest is often restored in a few decades. Nevertheless, this has also allowed invasive species to thrive.

The best time to visit is the Austral winter (May to October). This time of the year has moderate temperatures and less rain. Mornings are usually sunny, though towards noon clouds start blowing from the east. The mountainous inland usually experiences fog in the afternoon and rain in the evening, but the weather usually clears during the night. Fog is one of the greatest dangers for hikers on Piton de la Fournaise (see the Stay safe section below).

The ascent to the volcano takes place on the western side, which has better weather conditions. The mountain provides cover from the trade winds coming in from the east. On the western slope of the mountain it can rain 200 mm or, exceptionally, 1 m in one day (!), and the eastern slope gets even more rain.

With 12 m of rain every year, Réunion is together with Bengal one of the rainiest places in the world and holds the records for most rain in 12, 24, 72 and 96 hours. If you nonetheless decide to visit during the rainy season, do follow the weather reports and be aware that cyclones are a risk during this time of the year.

Snowfall is possible on the summit, but rare. It was last recorded on two days in August 2003.

• Piton de la Fournaise 1:25 000, 4406 RT. Publisher: Institut Geographic National. Series: Carte de Randonee topographique Top 25. About €11 locally and in French airports.

Since the Piton is an active volcano with frequent eruptions, the maps of the volcano and paths in guidebooks may be outdated - the paths are redrawn by Forestry services according to the current situation.

The N3 route des plaines ("road of the plains") cuts a diagonal in the island, from Le Tampon to the eastern shore. A clearly signposted road, Route du volcan, forks off from it and goes in the direction of the volcano (le volcan) and the Pas de Bellecombe. The hamlet of 🌍 Bourg Murat is the last opportunity to stock up on supplies, and you can also find a volcano museum there.

After a few kilometers the local road becomes a well-maintained forestry road, and in the final kilometers it becomes a well-maintained track. The road first goes through Alpine meadow landscape before it crosses the desolate volcanic landscape of Plaine des Sables, part of the outer caldera. There are several viewpoints along the route. Just before the parking lot, there's a road to the left leading to the Gite du Vulcan.

Park your car at the 🌍 parking lot near the Pas de Bellecombe. This place features a small kiosk, a toilet and a viewing platform. From here you'll start your hike into the caldera, that is, if it's not closed due to an eruption.

It is better to arrive early in the morning, for mid-day fog will set in. Remember that the northwestern coastal roads are frequently jammed, and that the route des plaines and the volcano road are mountain roads, so it may take a while to drive there from Saint-Denis.

While you can see the volcano from a different angle here, including eruptions that take place on the eastern side, it is impossible to climb from the seashore onto the volcano. There are no paths or trails, the volcanic rocks are difficult, fog may set in, etc., so the only access is from the other side as described above.

However, driving on the N2 coastal road at the bottom of the volcano is very interesting. The road cuts across volcano rock. Sometimes this rock is fresh - occasionally, erupting lava will cut across the road. The highway services then rebuild the road on top of the new rock and signpost the year of the eruption.

No permits or fees are required.

• 🌍 Commerson Crater. An older crater next to the route, about halfway between Bourg Murat and the volcano. (updated Dec 2017)
• 🌍 Plaine des Sables (along the route to the volcano). Reminiscent of a moon landscape, you will pass through this plain en route to the volcano. First the road follows the ridge above, where there are good views over the plain so why not stop and take some photos? Then the road descends into it and turns into a track with potholes. If you like, you can stop here again, however you should not wander off too far from your car in case the fog sets in; it's easy to get lost. 
• 🌍 Pas de Bellecombe (a few hundred meters from the parking lot). The access point to the inner caldera. From the viewpoint you can see the Formica Leo crater as well as the main dome with the summit. 

• 🌍 Formica Leo. This extinct crater is the first attraction along the path, a 30-45 minute walk from the gate. You can climb it and look into the volcano without having to go all the way up to the main craters which takes several hours. 
• 🌍 Chapelle de Rosemont. This rock formation forms a natural shelter. It's about one meter in size, and was created by a gas bubble in liquid lava. 
• 🌍 Bory Crater (cratère Bory). The western and the smaller of the two main craters. It was named after the explorer leading the 1801 expedition to the summit (2,631 m above sea level), which is located at the western side of the rim of this crater. Unlike its bigger neighbor, it existed already when the island was colonized. (updated Dec 2017)
• 🌍 Dolomieu Crater (cratère Dolomieu) (at the end of the path). With a diameter of 1000 m, and much deeper than the former, this is by far the biggest crater of Piton de la Fournaise. It emerged in 1791 at 200 meters in width and has grown in size ever since. 
• 🌍 Cratère Rivals. A small cone on the side of the main volcano, accessible by a path. 

In addition there are several smaller volcanic craters here and there. You can also find different forms of congealed lava, and lava caves that were created when the surface of the lava stream has cooled off and congealed, but the stuff below has stayed hot enough to flow further.

Eruptions are popular with locals and visitors alike, making the volcano a busier attraction than usual. Volcanic eruptions do not follow the same scheme every time, for example they can take place in many different parts of the volcano, though usually through the main crater at the summit. The intensity and duration of the eruption also varies. The inner caldera is off-limits during eruptions, and other parts of the area might be too if lava runs down the mountainside or an eruption takes place outside the inner caldera. Eruptions can also be seen from the air, onboard a sightseeing flight.

See also: Volcanoes#Stay_safe

See also: Hiking in Réunion, Mountaineering

The only access to the inner caldera is by foot from the parking lot through the Pas de Bellecombe gate. Thanks to this, it is easy to shut off access in the case of an imminent eruption. There might also be other advice posted at the gate. Entering the area is free.

The hike is not technically challenging, but walking on the uneven volcanic rock can be uncomfortable. You will first walk down stairs to the caldera floor, and then follow a path marked by white markers to the dome and up to the main crater. Walking from the gate to the crater will take you around 4 hours, and you should budget at least 10 hours for the whole 14.5-km roundtrip, or even a couple more hours if you plan to walk around the crater. Also, at the end of the hike, you need to walk up those same stairs to the gate.

For full detailed information about the hike, see Hiking the Piton de la Fournaise.

Sightseeing flights by helicopter and ultralight planes are available. Prices are about €200/person. As the weather and visibility usually gets bad in the afternoon, choose an early flight. When the volcano is erupting, night flights are available. Tour companies offering these flights include Tropicalement Votre and Air Aventures.

In the beginning of an eruption, the authorities close access to the volcano, while experts map out the situation. Then, they generally open access to certain areas. Follow the instructions. It is probably much easier with a local person.