Katazoegahama Seaside Park is the island's straightforward beach day. The sand, campground, and sea views make it a practical summer stop, especially if you want Suo-Oshima to be more than a scenic drive.
It is not a wild beach, and that is part of the appeal: parking, facilities, and nearby food make it easy to use. Outside the swimming season, it is still a pleasant place for a sea walk when the weather is clear.