We approach Piton de la Fournaise, the "Peak of the Furnace," crossing a shifting lunar landscape as we near one of the world's most active volcanoes. This hotspot volcano, roughly 530000 years old and rising to 2621 m/8599 ft, sits within the Enclos Fouque, an 8 km/5 mi caldera that has grown by way of the same hotspot forces that shaped Mauritius--here reaching their most dramatic and visible expression anywhere in the Indian Ocean.
Within the caldera, two summit craters tell their own stories: Dolomieu, by far the larger, and Bory beside it, both ringed by pyroclastic cones recording individual eruptions. At Nez de Boeuf--the "Ox's Nose"--we pause 1000 m/3281 ft above the Riviere des Remparts, where ancient lava has carved dramatic gorges through the rock.
The Maison du Volcan explains how this hotspot operates, why it remains so active, and how its eruptions continue to build new sections of the island, from ash and pumice to entire black-sand beaches.
At the upper viewing area we walk the crater rim, calderas stretching out like a lunar landscape, testimony to forces both creative and destructive. On recent lava flows, pioneer plants have begun the slow work of colonising bare rock--the same process that, given enough centuries, produced the lush forests we crossed to get here.
Our return route re-crosses the island's volcanic heart, fertile valleys nestled between the ranges that protect them, before we arrive back in Saint-Denis for the evening.
Overnight in Saint-Denis, Reunion
 
Included Meal(s): Breakfast and Dinner