For a natural experience of a different kind, check out the steaming pools of Yunokawa Onsen. This place is known for its mineral-rich thermal waters.
When you've finished up at this naturally heated water source in Hakodate, why not check out Yunokawa Hot Spring, Fort Goryokaku, and Ekini Fish Market? They're not very far from Yunokawa Onsen and also popular with many tourists.