Onsen Hotel Kitahiyama, or Spa Hotel Kitahiyama is located in Kitahiyama town, about 2 hours by car from Hakodate. It has large bathrooms and they are open to public for fee. The fee is 500yen per adult and the bathes are equipped with body soap and rince in shampoo. So you need towles.
I've heard that it is so popular that it is always full in weekends. I dropped by to check if it is true. The building is new and clean. The batherooms have the following facilities: a sauna room, a cold water bathtub, a bubble bath, utase-yu, or streaks of water falling from above and people place their body to hit a water streak on the stuffed shoulder or other parts, an open-air bath, an ordinally inside bathtub and a shallow bath tub where you can lay your body. They have various kinds of bathes.
And, it's a good news for parents who have little children. A slide is also equipped. The hight is about 2m and it may not be an exciting one.
Water quality consists of sodium and it may contain a little sulfur. There was no display about water temperature, but I think it was around 41 digrees centigrade. There are from 15 to 20 sets of a shower and a water tap. I didn't mind the number because there were not so many people.
Akiko lives in a city next to Hakodate and loves to drive around Hakodate and surrounding area. I hope people who visit or live in the Southwest area of Hokkaido come to love the area, too. 函館の隣町在住で道南エリアのドライブ大好きAkikoです。道南を訪れたり、住んでいる人が土地を好きになってくれたらなぁ、と思います。