The Center for Sacred Art's Gregorian Chant Retreats are held at St. Andrew's House, a retreat center located in Union, Washington, at the southernmost point of Hood Canal.
There are many ways to reach Union; some involve ferry trips, which can be a fun and relaxing way to get there, but do take longer. This map of the Puget Sound area will give you a sense of some of your choices, depending on which direction you're coming from.
.For more help with pathfinding, refer to Mapquest.