Simoa is the name of a river which flows through the municipalities of Sigdal and Modum in Buskerud County, Norway.

The Simoa river runs from Lake Soneren through the municipality of Sigdal in a south-easterly course until it flows into Drammenselva at Åmot in Modum.

The river begins a few miles north of Lake Haglebuvatna where it is initially known as the Haglebu, later becoming the Eggedøla as it flows through the valley of Eggedal.

Notable examples include Winter at Simoa River which was painted during 1883 by Norwegian artist Frits Thaulow.

[1] It was developed for hydroelectric power by Midt Nett Buskerud AS, the utility company owned by Modum and Sigdal municipalities.