Îlet Sainte-Marie is one of the best known and most easily accessible islets in Martinique. It has 1.22 km of coastline. Its highest point is 14 meters above sea level.
It is located opposite the village of the town of the same name. He is known to form a tombolo with Sainte-Marie. A tombolo is a coastal strip made up of a levee of pebbles or sand, connecting an island to the mainland.
The origin of the formation of the tombolos is the diffraction of the swells by an obstacle close to the coast. The waves diffracted on either side of this obstacle (here it is the islet of Sainte-Marie) converge behind it. Since the transport of sediments by the waves takes place in the direction of the propagation, an accumulation of sediments is observed along the line of convergence of the waves.
The tombolo is built and undone with the rhythm of the seasons. From November to April, when the swells come from the north and are more energetic, the sand spit forms.
In the case of Îlet Sainte-Marie, it is possible to get there on foot, more or less dry during dry season, that is to say from December to April. Once on the islet, a path laid out by the Office Nationale des Forêts allows you to go around it.
From April, the trade winds lessen and move in an east to south-east direction. During this period, the tombolo gradually erodes.
In the past, the sands of the tombolo were taken to be used as construction material.
Îlet Sainte-Marie, made up of conglomerates and micro-conglomerates, is the northernmost witness to the underwater volcanic chain of the Vauclin-Pitault chain. Crystallizations of zeolites of hydrothermal origin are present between the elements of the conglomerate.
The whole of Sainte-Marie islet is protected by a biotope protection decree, in particular because of the presence of birds that come to nest there, such as the Roseate Tern.
