What to know
Designated as a quasi-national park and located just 20 kilometers north of Hakodate, Onuma Park (大沼公園, Ōnuma Kōen) is famous for its scenic lakes dotted with islands and the majestic Mount Komagatake volcano.
Onuma Park is easy to visit as a day trip from Hakodate or as a stopover between Hakodate and Sapporo, since most limited express trains between the two cities stop at Onuma Koen Station, the park's centrally located railway station.
The most attractive area lies between Lake Onuma (large lake) and Lake Konuma (small lake) and can be explored entirely on foot. Pleasant walking trails let you discover the lakes' peninsulas and islands, several connected by small bridges, with walks ranging from 15 to 60 minutes.
Bicycle rentals are available (typically 500 yen per hour or 1,000 yen per day). A cycling course circles Lake Onuma (about 10 kilometers), though it follows the main road rather than the lakeshore for most of the way. Still, it's a nice way to explore the area.
During warmer months, sightseeing boat tours depart every 40 minutes and last about 30 minutes (1,460 yen per person). Other activities at Onuma Park include canoeing, tennis, golf, fishing, and camping.
From Hakodate Station, Onuma Koen Station is about 30 minutes by limited express train (1,840 yen, seat reservations required) or 40 minutes by local train (680 yen, all unreserved). Most limited express trains from Hakodate to Sapporo make a brief stop at Onuma Koen Station.