Lake Ciecere (Latvian: Cieceres ezers) is a lake in the southern part of Latvia, near the town of Brocēni in Saldus Municipality, Latvia. The lake has the status of a nature reserve.

The area of the lake is 276.8 hectares. The lake is stretched from north to south; its length is 9.5 km, and its maximum width is 0.4 km.

It is a proglacial lake located in a furrow and is the most expressive example of this type of lake in Latvia. In some places the lake is reminiscent of a river. It is sandy and muddy. Its shores are in places cliffs. One large island is Oak Island (Latvian: Ozolu), which has an area of 14 hectares.

From 1923 to 1977 this island had the status of a natural monument, and from 1977 to 1999 it was a botanical reserve.

The rivers Dunupe and Mazupe flow into the lake, and the river Ciecere flows out of it.

Previously, it was believed that lake has a maximum depth of 50 m, but measurements carried out in 2000 showed that it is no deeper than 22 m.

There are seven species of fish in the lake, including common carp, northern pike, European eel, and zander.

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