In chapter 9 of Germania, Tacitus, employing interpretatio romana (a process in which what an author deems Roman equivalents are listed in place of non-Roman deity names), says that the Suebi principally venerate "Mercury", and that they regard it as sacral to offer him both human and non-human sacrifices on specific dates (unprovided).
The Suebi also worship "Mars" and "Hercules", whom they appease by offering animals in a traditional manner.
Tacitus adds that a part of the Suebi, however, venerate "Isis", although he admits that he doesn't know how worship of Isis could have been imported: Latin: Birley translation: Rives translation: While Tacitus's "Mercury", "Mars", and "Hercules" are generally held to refer to Odin, Tyr, and Thor respectively, the identity of "Isis" has been a matter of debate.
B. Rives comments that while, in Tacitus's time, the cult of Isis was widespread and is well attested in provinces on the border of Germania, Tacitus's identification is problematic because the cult of Isis seems to have spread with Greco-Roman culture.
[4] In a 2012 paper, Joseph S. Hopkins and Haukur Þorgeirsson propose a connection between a Vanir goddess, particularly Freyja, and the ship symbolism of the "Isis" of the Suebi.