Wiesensee, Reservoir in Westerwaldkreis, Germany.

Wiesensee is a reservoir located in the Westerwaldkreis region of Rhineland-Palatinate, fed by natural streams running through the landscape. The body of water features a spacious shoreline with varying terrain and vegetation patterns around its edges.

A pond near Stahlhofen and Pottum was documented as early as 1270; by the late 18th century it had silted up into the swampy Seewies. In 1971 a joint association of the neighbouring municipalities dammed the streams on that land, creating the Wiesensee to promote tourism, improve the landscape and support fishing. In 2023 the water was fully drained for repairs to a dam flap.

The lake's name echoes the Seewies, the marshy meadow that covered this ground before the 1971 damming. Each October until 2023 the water was drained and the catch celebrated at a fishing festival; every three years the Vereinsring Pottum holds a Sommernachtfest on the shore.

The lake bed has been dry since February 2023, so the roughly 6.5 km loop path now runs around a meadow where trees and bushes have grown; mowing with special machinery began in November 2024. Refilling is expected from early 2027. Bus lines 477, 480 and N47 link the site with Westerburg and Rennerod.

In winter, the surface often freezes over and creates a natural ice field where visitors can ice skate. The frozen water becomes a popular spot for winter sports and outdoor activities among local visitors.