There is complicated the coastline in Dogashima in Nishi-izu, and there are small islands which float in a sea. You can enjoy this view fully imminently by sightseeing boat. The best highlight in the course is the skylight cave designated as a national natural monument. The condition light comes in from the ceiling of the cave is mysterious and beautiful. A sightseeing boat slips through the inside in the cave, and you can be satisfied with the scenic beauty nature produced.