is a small island with a circumference of about 700 meters and an area of 2.4 hectares, floating at the entrance of Muroran Port.
Legend has it that when the British ship Providence arrived in 1796, a sailor, Hans Olson, died in an accident and was buried there, and that black lilies began to bloom around that time as if to repent Olson's death. Among maritime professionals, the island is known as Olson Island.