A memorable puzzle from the Russian science magazine Kvant:
How can a goat, a head of cabbage, two wolves, and a dog be transported across a river if it’s known that the wolf is ‘culinarily partial to’ goat and dog, the dog is ‘on bad terms with’ the goat, and the goat is ‘not indifferent to’ cabbage? There are only three seats in your boat, so you can take only two passengers — animal or vegetable — at a time.
(You can keep order within the boat.)