The island is located in the city center, near the Cathedral Island. Its area is about five hectares.[3]
Its name derives from the Church of St Mary on the Sand, which is located on it. The island is also home to St. Anne's cemetery chapel, the Augustinian nunnery complex and a monument to Cardinal Kominek. Two pedestrian promenades are located on the edge of the island. These are the Boulevard of Stanisław Kulczyński and the Boulevard of Piotr Włostowic.[3]