Eiswoog, Reservoir in northern Palatinate Forest, Germany.

The Eiswoog is a reservoir of about 2.7 hectares on the Eisbach stream in the Stumpfwald, southwest of Ramsen. It runs south to north in the valley floor near the stream's seven springs, at 347.8 m above sea level, and extends up to 200 m into the mouths of the Eisbach, Hollerbach and Habersbach. Its dam crest carries the Seehaus Forelle hotel-restaurant.

The Eiswoog was probably a natural lake, first dammed in the Middle Ages, when it served as a fishpond for Ramsen Convent, founded in 1146. In 1812 the ironworks owner Ludwig Gienanth bought the nationalised "Eisenwoog" and raised and reinforced the dam to supply hydropower to his works on the Eisbach, expanding the water surface to its present size. The dam burst after storms on 12/13 April 1819 and again on 4 August 1875, flooding Ramsen and parts of Eisenberg.

The term 'woog' is a regional name for lakes that once powered watermills and other craft workshops throughout the Palatinate area.

A three-kilometer loop trail circles the lake with level paths and viewing points suitable for wheelchairs and strollers. The walk is easy to follow, though sections pass through shade and can become damp after rain.

The Eistal Viaduct north of the dam is 35 metres high and, at 250 metres, the longest railway bridge in the Palatinate. It carried trains until 1988 and has stood out of service since; the weekend trains of the Eis Valley Railway now end at the Eiswoog halt. A viewing point lies at its eastern end.