This entry is guide-book style for folks visiting Japan who want a little sumtin-sumtin that`s not in the Lonely Planet.
Onuma is listed in the JNTO brochure as an attraction outside Hakodate, and it`s totally worth the day trip. For about Y550, you can take the local one-car train to the Onuma-koen (Onuma park) stop. Onuma-koen is a quasi-national park. We`re not sure if it`s not quite a park or not quite national, but so be it.
Don`t get off at Onuma, or you`ll have a drab extra few km to walk. Make sure you wait for Onuma-koen. The station is small, but had a locker big enough for our two packs (Y400). Unlike most eki, this one opens onto a quaint touristy scene, with bicycle rentals and small retail shops. Rent a bike for Y1000 each (there might be cheaper/nice options at the bike shop by the post office two blocks ahead on your right), and you have a whole day of fun ahead of you.
There`s a bike path around both of the main lakes (there are three all told, formed by volcanic activity in the area). They`re all incredibly scenic, and there are dedicated bike trails for the most part.
The Japanese crowds seem to stick to the retail area right by the eki. To avoid them, head around the biggest lake counter-clockwise (just head out straight on the road away from the eki). After a few km (and some picturesque viewing spots along the lake - Hillary reminds me to warn you about the snakes), you`ll see on your right a Shinkansen that has apparently come here to die. It`s one of the many sights at Naka-something Onsen, an amazing little side destination off the main street. Turn right across the tracks just after the Shinkansen that don`t go, and you`ll soon arrive.
There, first enjoy pleasant campsite bathrooms (in the U.S., also known as nasty stinkholes. In Japan, you`ll find sanitized surroundings and heated toilet seats). Then strike out for Stone Crazy, the local sculpture garden. After a nice stroll through the modernist interpretations, head back to the onsen itself for a hot spring soak, or for lunch (Y850 for a set - the mixed tempura patties were excellent). After all that, you`ll be ready for a round of Park Golf. Park Golf is kind of a cross between croquet and mini-golf. You get a mallet that looks something like a short driver, and a ball that`s like a bocce ball. You head out to a course that looks something like Honey I Shrunk the Golf Course. You may have to wait to play behind a foursome of Japanese players in their golf finest - plaid sweater vests and all - but it`ll be worth it. The par 5 133 yard holes are challenging, but the satisfying clank when you sink that 14 footer is worth every inch. (Y500 for 27 holes, Y300 to rent equipment, unless you brought your own from home).
Back on the road, you`ll continue for a total of maybe 12km. Back at the eki, you`ll find a truly scenic walking trail over maybe 10 bridges on a bunch of little islands. But if you`re tired of exertion, you may be better off getting some Hokkaido Custard at one of the (many) omiyage stores, or sitting down at the local microbrewery, which serves a suprisingly good IPA (Y550 for a glassful). After all that exercise, the seats somehow seem more comfortable, and the service is great. Hop on the afternoon train back to Hakodate, or continue on to Toya-ko Onsen or Sapporo.