Großes Meer, nature reserve in Lower Saxony, Germany

Großes Meer is a 24.6-hectare nature reserve in Eydelstedt, Lower Saxony, centred on a shallow lake also called Holter Meer. The open water covers 11.2 hectares, averages 1.09 metres deep and reaches 1.55 metres about 70 metres off the eastern shore. The lake is bordered by a 1,600-metre shoreline, with a steeper eastern bank and a narrower western bank.

The lake formed approximately 14,000 years ago after the last ice age as a depression left by moving glacial ice. The area has been under protection since 1942 and was once significantly larger before groundwater lowering in the 20th century reduced the water surface.

The name reflects what was once a much larger body of water that shaped the local landscape. Today the place serves residents and visitors as a space for walking, bird watching, and fishing where nature remains central to how people use the land.

Visitors should stay on marked paths to avoid disturbing plants and animals, and keep dogs leashed at all times. The area offers good opportunities for bird watching and walking through the flat landscape, with maps and information available from the Diepholz district authority.

The lake's surface shrank from 16.7 hectares in 1958 to 11.2 hectares today, probably because of groundwater lowering in the 1960s. A local legend says a Christian preacher was killed in a sacred forest on this spot, and the forest then sank to form the round lake.