I am thinking of visiting Victoria, BC in Canada and then going to Seattle, WA in the US, with the Victoria Clipper ferry.
I am a national of a country under the Visa Waiver Program. I think that if I enter by air, I need to fill an ESTA form. If I enter by car, I don't need one, I can fill a form when crossing the border.
With the ferry, what is the procedure? Should I necessarily have an ESTA?