Boats, presumably powered by whale oil, are a useful mode of travel for those going to and fro between Dunwall's districts.
Corvo chiefly comes into contact with Samuel Beechworth's boat, the Amaranth.
Trivia
Oddly, the boats inside the Lifeboat Dock in Kingsparrow Fort also have Amanranth on their sides. This may have been an oversight on the developer's part or may mean Samuel's boat and the others are of the same brand.
Gallery
Concept art of boats on the Wrenhaven River.
A boat on its side near two life preservers.
A shelter made from boats.
A man in a boat.
A large boat filled with packages.
Boats in storage.
A boat up against a wall behind Granny Rags's house.
Samuel's boat.
A mat reading "Welcome", found in Samuel's boat.
A large boat filled with packages near Kaldwin's Bridge.