Hammervatnet[2] is a lake in Levanger Municipality in Trøndelag county, Norway.

The 6.03-square-kilometre (2.33 sq mi) lake lies on the north side of the village of Åsen.

The European route E6 highway runs along the eastern tip of the lake.

The main outlet of Hammervatnet flows into the Hoplafjorden, an arm of the Trondheimsfjord.

There are two large islands in the lake Hammervatnet: Innerøya and Ytterøya.