In Akkeshi Lake, there is Oyster Island (officially Benten Island) and a small Benten Shrine.
The founding of this shrine is not clear, but it remains in records from Kansei 3 (1791), and it is also recorded that a festival was held in Bunsei 3 (1820).
Also, previously, this island's area was wide, to the extent that there were also health resorts and traditional Japanese restaurants, but currently, it has become small due to ground subsidence.