Theikenmeer, Protected nature reserve in Werlte, Germany.

The Theikenmeer is a 250-hectare nature reserve (NSG WE 010) in the Samtgemeinde Werlte, Emsland district, between Sögel and Werlte. It covers a raised bog, the Wehmer Dose, with a lake inside it; both are resting places for migrating waterbirds. After rewetting, the bog again supports species typical of raised bogs.

The area between Sögel and Werlte was declared a nature reserve by decree on 16 November 1936, with the Emsland district as the lower nature conservation authority. Illegal drainage dried out and silted up the Theikenmeer by the mid-1970s; young conservationists stopped the drainage and re-wetted the lake with dam structures. It was dredged again in the 1980s, the neighbouring Wehmer Dose was added, and in 2015 the area became part of the Hümmling Nature Park.

In a converted large barn near the Theikenmeer there is an exhibition on the natural history of the region, focusing on the Theikenmeer and the neighbouring bogs. The reserve lies on the Hümmlinger Pilgerweg, on the 26.7 km Sögel–Werlte stage.

The reserve is accessible through two marked hiking trails: a longer circular route with information stations and a shorter path to viewing areas. Wear sturdy footwear and stay on marked paths to protect the fragile habitats.

The reserve is home to rare plants like round-leaved sundew and cotton grass that nearly vanished from the region. It also shelters dragonflies and snakes that can only survive in these boggy wetlands.