One of the places I feel most at peace is San Juan islands. They are located four hours away from Portland and we are trying to go there every other year. The islands cut the waves and allow the ocean water to look glassy and reflective, like that of a lake.
I normally use sienna for under paintings. I read about using blue- dark ultramarine color for pictures of water. I tried it on this picture and, even thought it felt odd, I'm pleased how it turned out, so there will be more blue under paintings for sure.