I just thought of this yesterday while pondering the whole 'harpoon another ship idea' after a fishy bit me south of Hotaru.
Why not add whales as monsters, in dark blue water, and add harpoons, and when you kill the whale you gain so much 'whale oil'. You then take the whale oil and put it in your lamps and whatnot to make them light. Your torches in turn would have something like 'Whale Oil 50%'. When the Whale Oil in the torch reaches zero, you can't light the torch/lamp/etc until you refill it with whale oil.
You might also could use the 'whale meat' for food.. and plus, this gives us a chance for a bunch of GK Hippies to come out of the shadows and protest... this also brings about Kingdom competition for whale oil, which would lead to (finally) more naval wars simply for Whaling rights. Whale bones could be used for brushes or certain types of furniture, and maybe some types of jewelry or something.
Either way.... would be nice
