Chiusi lake is in the province of Siena, municipality of Chiusi. In the past, residents of Chiusi called the lake "Light of the Moon" because a legend told that in the calm of the night the beautiful god of the sky, would come to stare at her reflection in these waters. The lake occupies three hundred hectares of surface area with a depth of five meters. It is connected to the Montepulciano Lake by the Passo alla Querce Canal. This body of water represents, along with Montepulciano Lake, the remains of the marshlands that once covered the bottom of the Valdichiana. Although not considered a Natural Reserve, the lake and its terrain are a natural environment for protected wildlife and plants typucally found in humid environments. It is a resting and nesting place of aquatic birds in their migration: waterplants and plants that grow best in full sunlight. The acquatic wildlife of this lake historically represented an important food source for the population.