Growing up beneath Tennessee skies, surrounded by a multitude of waterways, I thought I knew the color blue well. Blue can be frothy, almost as white as the clouds on a bright April morning, or deep and temperamental, nearly black, just before winds stir up a poisonous yellow-green that means tornadoes will soon start grabbing at the land.

I thought I knew every trick of that color, until an afternoon in May 1991 when my husband and I crossed the sand of Coronado Beach and stood there, goggle-eyed, speechless. We had finally encountered blue.

Blue is spiritual.

We lived a mile off Loma Point in San Diego for three months, narrowly surviving on bare minimum military pay and young love. Our diet was mostly 3-for-$1 burritos so that we could put a little money toward touring the city, the suburbs, and the coastline whenever possible. I walked from work…