Eru Bay is the wide, shallow bay west of the Käsmu peninsula — a long curve of pine-fringed coast with very gradual sand bottom, looking south to the village of Vergi. A small fishing harbour at Vergi, the only village on the bay's southern shore, has a couple of seasonal cafés and a wooden pier popular at sunset.
The bay is one of the best places for birdwatching on the Lahemaa coast: in spring and autumn migrating cranes, geese, and shorebirds use the shallows and the reed beds along the western shore. The reed-bed boardwalk at Eru is a 30-minute drive west from Käsmu and is an easy add-on to a peninsula visit.