Although nearly all are in locked boxes either in the four areas or within houses in those four areas there are a couple of additional locations: one is down on the beach, the other is in te spaces or corridoors between locations (try mailmans house between Serfside and Splitwood). One area that eluded me for a while was behind the statues that carry the fish gods eyes in Rust Grove. Other than that, bash down every locked door and take the opportunity to walk around (rather than run) and see the areas you missed while chasing spirits.