Located off the Atlantic coast in the bay of the municipality of Le Robert in Martinique, the La Grotte islet comes from the underwater volcanic chain of Vauclin-Pitault and, more precisely, from the initial Le François - Le Robert episode dated from the medium Miocene. Elongated and conical to the south, it displays a facies of hyaloclastites and massive flows. The islet of 14 acres (5.7 ha) culminating at 124 ft (38 m) shelters a very heterogeneous and discontinuous vegetation where a pioneering natural flora and an anthropophilic flora coexist near the houses. There are notably country mulberries (Maclura tinctoria), a plant species rare in Martinique. Since October 2002, a biotope protection zone has been established over the entire islet, which became a registered site in July 2007.