Grand Marais (German: Grosses Moos) in Seeland is a region in Switzerland, at the foot of the first mountain range of the Jura Mountains contained by the three lakes of Morat (Murten), Neuchâtel and Bienne (Biel). Before the huge hydrological works Jura water correction, it was a marshland that covered 62.5 km² (24.1 sq mi). Before the correction the entire Grand Marais, along with the whole of Seeland was prone to very severe recurring floods.

This article includes a list of references, related reading, or external links, but its sources remain unclear because it lacks inline citations. (June 2022)

After the Jura water correction, the former marshland has become very valuable agricultural land and made the whole area the most important region in Switzerland for growing vegetables.

The main town and centre of vegetable trading is Müntschemier.

There are two prisons with surrounding agricultural compounds: Bellechasse (Witzwil) and St. Johannsen.

• Grand Marais, Seeland in German, French and Italian in the online Historical Dictionary of Switzerland.
• Bellechasse in German, French and Italian in the online Historical Dictionary of Switzerland.
• Anstalt Massnahmezentrum St. Johannsen
• ETH-UNS Case Study «Perspektive Grosses Moos – Wege zu einer nachhaltigen Landwirtschaft»

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