Piton de la Fournaise is the most frequently visited site on Réunion. The Piton de la Fournaise massif covers around one-third of the island's surface area, peaking at 2,632 metres altitude. Its slopes shelter a significant proportion of Réunion's biodiversity. It is also one of the most active volcanoes on the planet.

The Volcano Observatory

Located at Plaine des Cafres, the Volcano Observatory is part of the Institut de Physique du Globe (or Paris Institute of Earth Physics) and fulfils a monitoring and research role. In order to predict the next eruption, monitoring apparatus at the Piton de la Fournaise Volcano Observatory constantly records seismic movements and deformations occurring in the region. 

Réunion polders

Locals and visitors on Réunion flock to see the show put on by the fire fountains and lava flows, especially when they run down into the ocean, giving off plumes of smoke.

The island grows with each eruption. In April 2007, Piton de la Fournaise poured out some 130 million cubic metres of lava at Tremblet, to the southeast of the island, creating 45 hectares of new land in the Indian Ocean. 

It took over six months to rebuild the national highway, which had been cut off over a 1,500-metre stretch. However, this could only be done once the lava had cooled down. In some areas, the layer of lava was more than 60 metres thick and continued to smoke.

Hundreds of fish were killed, including some previously unknown species. They were discovered off the coast of Saint-Philippe where the lava ran into the ocean.

The Réunionnais people and the volcano

Because the caldera, within which most of the eruptions occur, is uninhabited, Piton de la Fournaise does not represent a danger for the island's population. However, eruptions can occur outside the caldera, as was the case in 1977 and 1986.
In 1977, lava flow engulfed several houses in the town of Sainte-Rose before coming to a halt on the threshold of Notre Dame des Laves church. According to some, this was a miracle and led to the foundation of the Volcano Observatory.
Since then, it has been possible to predict these rare eruptions and the people living near the volcano (in the villages of Tremblet and Bois Blanc) have been evacuated where necessary.

Fauna and flora

Vegetation quickly re-emerges after lava flow. It begins with the whitish lichen which gives the recent flows on Grandes-Pentes their light colour, contrasting with the very dark younger lava. After that, several plant species appear in the crevices of the lava, such as ferns and shrubs that colonise these fertile soils. The native forest then gradually gains ground.

In the Enclos, near the Bois-Blanc rempart, there is an educational trail, leading off the N2, explaining how lava flows are gradually vegetated.
The upper areas of the towns of Saint-Philippe, Sainte-Rose and Saint-Joseph shelter a complete biological reserve including all the plant formations native to the Coloraie du Volcan massif from the coast (around 500m) up to the peak of Piton de la Fournaise.