壹岐島
The "tsutsu" part of the names of the three gods has a connection to the planets, and there is a theory 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. Also, the locations of Tsutsu on Tsushima Island, Tsutsuki on Iki Island, Tsutsuki in Itoshima, Fukuoka prefecture are in the arrangement of these three Orion stars.