Simpson Bay Lagoon is a large lagoon in the west of the Caribbean island of Saint Martin. The border between the French and Dutch halves of the island runs across the centre of the lagoon. There are two small islands that lie in the lagoon: the larger, to the north, is within the French region of Saint-Martin, the smaller, to the south, is on the Dutch Sint Maarten side. The lagoon is connected to the Caribbean sea via a small channel to the north, which flows into Baie Nettlé in Saint-Martin. Sint Maarten's airport, Princess Juliana International Airport lies close to the lagoon's southern shore.