From Ytteroy to Swansea (UK)

My great grandfather was born on the island of Ytteroy (off Levanger). He left Norway before 1886 and settled in Swansea (UK). How might he have got to Swansea? By sea I presume? But......from where....Levanger, Trondheim, Bergen......??????? Were there any sea routes, at this time, from Ytteroy, or near by, to Swansea? Or is this a question that cannot be answered? Many thanks