The Columbia river is amazing. Quite understandable the first European explorers believed this to be a bay. The Astoria Megler bridge connects Washington to Oregon, had I taken the direct way along the 101 through Washington, I would have crossed it. The bike lane is very narrow I was told, so six miles of trying to not hit a railing is maybe not so much fun. And it is impressive to look at even from far.
At Stevenson state park you get this river on one side and the pacific ocean to the other.
You also get loads of giant mosquitos and and giant elks blocking the bike trail for free.