River Crossing Puzzles: How to Solve Them

River crossing puzzles are some of the oldest brain teasers in the world, and they still trip up grown-ups. A small boat, a few passengers and one big problem: some of them cannot be left together. This guide explains the classic puzzle, then gives a step-by-step method that works for harder versions, with examples from our game Silly Raft.

How it works

In the classic version, a farmer must take a wolf, a goat and a cabbage across a river. His boat holds the farmer and only one of them. If the wolf is left alone with the goat, the wolf eats the goat. If the goat is left alone with the cabbage, the goat eats the cabbage. This riddle has been told for over a thousand years.

Every river crossing puzzle mixes the same three rules: the boat has little room, someone must be on board to row it, and some passengers cannot stay together without a guard. Since the boat has to come back for the others, you always need more trips than you think.

Solving the classic puzzle

The trick is to spot the passenger who is part of every problem. The wolf wants the goat and the goat wants the cabbage: the goat is in both, so the goat must travel first.

First, take the goat across and come back alone. Then take the wolf over, and bring the goat back with you. Next, take the cabbage over and come back alone. Finally, go and fetch the goat. That makes seven crossings.

The key move is bringing the goat back. It feels like going backwards, but it is the only way to win. Most river crossing puzzles hide a move like this one.

Step 1: List who cannot stay with whom

Before any trip, write down every conflict. In Silly Raft, you do not even need to read: the rules of each level are drawn as cards at the top of the screen, with a hungry animal, a mouth, then what it loves to eat. The fox loves the chick, the chick loves the seeds and the rabbit loves the carrot.

Now look for chains. An animal that is both hungry and someone's snack, like the chick between the fox and the seeds, is your troublemaker. It is usually the one that travels first and the one you bring back.

Step 2: Check every place after every trip

After each crossing, check the bank you left and the bank you reached. A guard keeps everyone safe: in Silly Raft, nobody gets chased where Captain Twig the beaver is.

In Silly Raft, the raft counts too. If the otter rows the fox and the chick across without the beaver, the fox chases the chick on the way. A chase sends you back to the move before, but the crossing still counts. Later levels add a guard dog, who stops the others from eating but chases the rabbit himself.

Step 3: Plan the trips back

The boat must come back, so think about every return trip. An empty return is fine when both banks are safe. When they are not, bring a passenger back with you. From level 4 of Silly Raft, every level needs at least one return with a passenger, so the obvious plan never works.

Remember who can row. In Silly Raft, only the beaver or an animal with a little paddle drawn on it can row. From level 8, the otter can row too, so the beaver can stay behind to guard a bank. Just do not leave the otter alone with the fish.

Step 4: Keep track and avoid circles

Bigger puzzles are easy to lose track of. Draw two columns on paper, one for each bank, and write who is where after every trip. If you end up in a position you already had, you went round in a circle: go back and try another move.

In Silly Raft, stars compare all your crossings with the best solution, failed and undone ones included. Undo cancels the last crossing, but it stays counted. Restart puts the counter back to zero, so if you are lost, restart and follow your plan.

Try Silly Raft and more puzzles

Silly Raft turns the river crossing puzzle into a picture game, with a three-seat raft, a bear who takes two seats and animals who refuse to ride together. Picnic Squabble is another who-sits-with-whom puzzle, and Duck Canal asks you to plan ahead, even closing a gate you just opened.