The Ré island is located in the Atlantic Ocean. It is part of the department of Charente Maritime and the region of New Aquitaine. Its surface is 85 km² and it counts ten communes that make up the canton of the Ré island.
In the ancient times, a violent earthquake struck the region and it was at the origin of the separation of the continent. At that time, it was still an archipelago of 4 islets, but later, they were connected to form the island. The alluvial deposits and the construction of salt marshes allowed this attachment.
The island stretches over a length of 26 km and its coastline makes a total of 100 km with several sandy beaches, especially in the southern part. There is not much relief on the Ré island. This particularity has an impact on the weather of the island and is at the origin of the frequent rains in the region, especially in autumn and winter.
As highlighted above, the relief is almost non-existent in the Ré island. Its climax is barely 20 meters above sea level. It is located at the locality of Peu-des-amonts, in the town of Bois-Plages-en-Ré. The narrowest part of the island is the Martha's Isthmus which connects the eastern and western parts of the island. The isthmus of Martray is attached to the commune of Ars-en-Ré.