In Norse mythology, the Kerlaugar (plural form of Old Norse kerlaug "kettle-bath",) i.e. "bath-tub", are two rivers through which the god Thor wades. The Kerlaugar are attested in the Poetic Edda, compiled in the 13th century from earlier traditional material, and in a citation of the same verse in the Prose Edda, written in the 13th century by Snorri Sturluson.
Attestations
The Kerlaugar are mentioned once in the Poetic Edda. In the Poetic Edda poem Grímnismál, Grímnir notes that the bridge Asbrú "burns all with flames" and that, every day, the god Thor wades through the waters of Körmt and Örmt and the two Kerlaugar:
In Norse mythology, the Kerlaugar (plural form of Old Norse "kerlaug," meaning "kettle-bath" or "bath-tub") are two rivers that the god Thor wades through. These rivers are mentioned in the Poetic Edda, a collection of Old Norse poems compiled in the 13th century, and also cited in the Prose Edda, written by Snorri Sturluson in the 13th century.
The Kerlaugar are mentioned in the Poetic Edda poem Grímnismál, where Grímnir notes that Thor, on his way to council at Yggdrasil's ash tree, must wade through the waters of Körmt, Örmt, and the two Kerlaugar every day. The passage describes that the As-bridge (possibly Bifröst) is on fire, and the holy waters boil.
In the Prose Edda's Gylfaginning, it is mentioned that Thor wades through rivers to attend court, and the Grímnismál stanza is quoted to support this description. The Kerlaugar also appear in the list of rivers in the Nafnaþulur section of Skáldskaparmál.
The exact meaning and significance of the Kerlaugar are not entirely clear. Rudolf Simek finds the mention of the Kerlaugar strange and suggests they might be related to a lost myth about Thor. Guðbrandur Vigfússon and Frederick York Powell suggested that the name might have Irish origins and could be related to river names beginning with "Ker-" or "Char-."
Thor is often depicted crossing rivers in Norse mythology, which may symbolize his frequent interactions with the jötnar (giants) and their realms, as jötnar are often associated with water. The connection between jötnar and water is significant in Norse mythology, with creatures like Jörmungandr, the world serpent, dwelling in the ocean.
In the Prose Edda, the rivers are mentioned twice, once in Gylfaginning and once in Skáldskaparmál. In Gylfaginning, High says that Thor wades through rivers to go to court, and then quotes the above cited Grímnismál stanza in support. In Skáldskaparmál, the Kerlaugar appear in the list of rivers in the Nafnaþulur.
Theories and interpretations
Rudolf Simek comments that the meaning is "strange" and may point to an otherwise lost myth about Thor. On the other hand Guðbrandur Vigfússon argued that it and several other river names in the same poem were Irish in origin and related it to river names beginning in Ker- or Char- such as Cherwell. He and Frederick York Powell rendered it "Charlocks" in Corpus Poeticum Boreale.
Thor frequently crosses rivers in the mythology; John Lindow suggests this is due to the large amount of time he spends in the realms of the jötnar, "who live on the other sides of boundaries", and points to a symbolic connection between jötnar and water, citing the ocean-dwelling Jörmungandr as an example.