Käsmu Bay (Estonian: Käsmu laht) is a bay in Lääne-Viru County, Estonia.[1]
The bay is located between Käsmu and Vergi Peninsula. The bay's width is up to 4 km and depth of 12-27 m.
Käsmu Stream and Võsu River flows into the bay.
Borough of Võsu is located at the bay.
The bay is under protection (Lahemaa National Park).