Åsnen is a large lake in southern Småland, Sweden, roughly 150 km² in size. The river Mörrumsån flows south from Åsnen into the Baltic Sea. The lake lies south of Alvesta and Växjö and northwest of Tingsryd and is the second-largest lake in Smålands, after Bolmen. Approximately 19 km² of the lake's area is occupied by small islands. Åsnen has many small bays and islands, the largest of which is Sirkön.
Fruits (mainly apples and strawberries) are grown in the southern parts of the lake area, including on Sirkön.