[1] The Sumiyoshi sanjin are regarded as the gods of the sea and sailing.
[2] According to Japanese mythology as written in works such as the Kojiki and Nihon Shoki, the Sumiyoshi sanjin were born together with the Watatsumi Sanjin (綿津見三神) when Izanagi performed a purification ceremony after returning from Yomi.
The tsutsu part of the names of the three gods has a connection to the planets, and there is a theory that suggests the Sumiyoshi sanjin are the deification of the three main stars in the Orion constellation.
In the olden days the Orion constellation was used for navigational purposes so it was perhaps for this reason that they were deified.
Probably the most notable appearance is in The Tale of Genji where it is the luck deity which the father of the Akashi Lady prays to help his daughter find a husband and secure her well-being.