De Spiegel is an access point on the Spiegel- en Blijkpolderplas, a nature area of roughly 280 hectares located northeast of Nederhorst den Berg in the municipality of Wijdemeren.

The lake was formed through peat extraction followed by sand extraction, and in places reaches depths of 45 metres.

The water is exceptionally clear, making the Spiegel- en Blijkpolderplas one of the most celebrated diving destinations in the Netherlands, with a dedicated diving zone on the northern shore.

Boat access to the lake from the Vecht is only possible through the Zanderijsluis locks, and passage onward to other waters is not permitted. The limited access keeps boat traffic low, particularly in the evenings.