Instead of driving from Sapporo directly to Hakodate we decided to break the route in two and so spent part of a day, and a night in Toyako on Lake Toya. The lake is in a caldera formed by volcanic eruption about 110,000 years ago. It is almost circular, as length is 10km & width is 9km. Nakajima Island sits right in the middle of the lake. The caldera lake is so deep, ~400ft, that it never freezes during the frigid winters (90 consecutive days below freezing). It is also considered one of the most, if not the most, transparent lake in Japan. The area is still populated with many active volcanic sites; the two most recent eruptions were in 1977 & 2000. I don't plan to buy property in the area any time soon - or ever !
Hakodate here we come.
Ciao for now