Preserved in Snorri Sturluson's Skáldskaparmál (4) only, they deal with Thor's fishing expedition with the giant Hymir, where the god attempts to kill Jörmungandr.
Snorri Sturluson's Skáldskaparmál (4) provides a detailed account of Thor's fishing expedition with the giant Hymir and his attempt to slay Jörmungandr.