It looks like this picture was taken from the inside of a cave, but it was really just some overhanging rocks. This is a great little beach spot in Deception Pass State Park on the north side of the bridge. It's called Lighthouse Point. You can get there by taking a short walk south along the shore from the Bowman Bay boat launch on the north side of the bridge. Or there is a somewhat more adventurous "secret" trail that drops down through the forest from an unmarked pullout on the highway just north of the Deception Pass Bridge. 

That "secret" trail is actually part of the Pacific Northwest National Scenic Trail (PNT) which, from there, continues south right over the Deception Pass Bridge (for westbound hikers). The PNT is an official 1,200 mile hiking route from Glacier National Park in Montana all the way to the Pacific shores of Washington State on the Olympic Peninsula. After crossing the bridge, westbound hikers will walk well down into central Whidbey Island and utilizes the Port Townsend Ferry crossing to get to the Olympic Peninsula. 

The curve of the boat's mainsail seems to flow naturally with the contour of Mount Baker. This was on a recent ferry ride to Orcas Island. My daughter and I were spending a few days at the Owl House in early April and took a day trip to the San Juan Islands. With a bluebird day like this in early spring, we couldn't pass on the chance to get out to the San Juans. There's nothing like the Salish Sea under a blue sky and the glacier-topped mountains in the distance.