Silhouette Island lies 20 km northwest of Mahé in the Seychelles. It is the third largest island in the Seychelles. It has an area of 20 km² and has a population of 135, mostly workers on the island. The main settlement is La Passe, where there is a hotel for visitors to Silhouette. The name Silhouette was given after Etienne de Silhouette (1709-1767), the French minister of finances under Louis XV.
The island is mountainous with five peaks over 500 meters in elevation; Mont Dauban (740m), Mont-Pot-a-Eau (621m), Gratte Fesse (515m) Mont Corgat (502m) and Mont Cocos Marrons (500m). As such it has some of the most dramatic scenery of the islands.
From the mid 19th century until 1960, the island was owned by the Dauban family, who were originally from France but had settled in Mauritius in 1830. The Dauban family were responsible for developing extensive plantations on Silhouette. There is a Mausoleum built in the style of La Madaleine in Paris Église de la Madeleine, where a number of the family members are buried including Auguste Dauban, whose business ventures were so extensive he earned the nickname, the "Rothschild of the Indian Ocean". The Dauban plantation house has recently been restored.
Silhouette Island is situated within a Marine National Park and is dedicated to environmental protection. It is one of the richest biodiversity hot-spots in the western Indian Ocean with many endemic and threatened plant and animal species. The island has a large area of primeval forest and supports the last known roosts of the Seychelles sheath-tailed bat Coleura seychellensis. The island is an Important Bird Area and is considered by the Alliance for Zero Extinction to be an important site for the survival of Critically Endangered species. The Nature Protection Trust of Seychelles manages conservation on the island and has a breeding centre for the extinct-in-the-wild Seychelles giant tortoises and Arnold's Giant Tortoises. In December 2006, the latter species was re-established in the wild. Conservation of the island is managed by the Nature Protection Trust of Seychelles.
The island is surrounded by a rich marine environment, including a coral barrier reef and granite cliffs. The coral habitats are exceptionally healthy and there are many good diving sites, although strong currents may limit swimming or water-sports. On a clear day, one can experience spectacular views of the north coast of Mahé.
The granitic island is reputedly a site of mediaeval graves of passing Arab sailors, although purported Arab graves date back only 200 years. Also there is a legend in the Seychelles that the corsair Jean-Francois Hodoul buried his treasure on Silhouette Island.