Île Saint-Joseph is the southernmost island of the three Iles du Salut

Îles du Salut

The Îles du Salut are a group of small islands of volcanic origin about 11 km off the coast of French Guiana in the Atlantic Ocean...

 in the Atlantic Ocean

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 off the coast of French Guiana

French Guiana

French Guiana is an overseas region of France, consisting of a single overseas department located on the northern Atlantic coast of South America. It has borders with two nations, Brazil to the east and south, and Suriname to the west...

. Twenty hectare

Hectare

The hectare is a metric unit of area defined as 10,000 square metres , and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metres and the hectare was thus 100 ares or 1/100 km2...

s in size, it is the middle in size. During the period when the islands were used as a penal colony

Penal colony

A penal colony is a settlement used to exile prisoners and separate them from the general populace by placing them in a remote location, often an island or distant colonial territory...

, the island was reserved for solitary confinement. At an elevation of 30 meters, it is also the lowest island of the group. Most of the island is covered with dense vegetation.