The IBA comprises the Piton des Neiges - Gros Morne volcanic massif, the highest land on Réunion with a peak elevation of over 3000 m and the meeting point of the island's three calderas of Cilaos, Mafate and Salazie. The summit area is mainly bare rock and scree, while the lower parts of the site, from about 2800 m down to 2000 m above sea level, are vegetated with native alpine shrubland. The site has a mountain hut but no permanent inhabitants and is used recreationally by hikers and climbers.