The Hummeln structure was confirmed, in 2015, as an impact crater in Småland province, Sweden.

[1] It is a 1.2 kilometres (0.75 mi) wide depression within Lake Hummeln and is estimated to have formed between 470 and 443 Ma ago, during the Ordovician.

[2] In the 1960s, mapping of the lake topography gave the first hints of an impact event.

[3] Further investigation led to more details such as breccia that firmly established the structure's impact nature.

It has also been suggested that this structure, the nearby Granby crater, and other coeval small craters in Baltoscandia may be connected to the Ordovician meteor event of 470 Ma.