Based on my pre-study of the recommended sightseeing routes, we first visited Otaru General Museum Unga-kan (Canal Museum). The museum occupies the northern section of a timber-framed stone storage building built in 1893 by a merchant from Ishikawa Prefecture used for storing grain and seafood. There are two exhibition rooms, the first focuses on the development of Otaru with displays related to the port and canals, herring fishing (some objects of which we had seen at The Historical Village of Hokkaido in Sapporo) and the trading between Hokkaido and mainland Honshuu. This was quite informative. The second focuses on nature and archaeology. There is a description outside that tells that the building complex that the museum is situated in is "One of the first commercial use warehouses built in the Ironai district immediately after the reclamation of the area. While the original construction consisted of the front right side of the building, further additions enclosed two courtyards to create a warehouse of truly grand proportions." The admission fee is 300yen and well worth it.

If you only have one chance to visit a museum in Otaru, this would be it. Quite informative, 45 mins max & 60mins if you can the Japanese description. Located right opposite the overrated Otaru Canal..