River crossing puzzles
Move everyone across a river in one small boat without leaving a forbidden pair behind.
Example
Example
An example to explore. No score or practice round is recorded.
Six boards with three to five travelers. Try small groups, forbidden pairs and a first lantern crossing.
Your level and your rounds are kept in this browser.
1 puzzle · No time limit
A crossing that would break a rule does not happen. The line under the scene says who would be left in trouble.
- Crossings
- 0 / 7
- Time
- 0:00
Get everyone across
Tap a traveler to put them in the boat, then press Cross. A round ends when everyone is on the far bank.
Far bank
Near bank
The river, with the near bank at the bottom, the far bank at the top and the boat between them.
Keyboard: Tab moves between travelers, Enter puts the focused one in the boat or back on the bank, C crosses, Z undoes, H asks for a hint, Escape ends the round.
Leave this board?
This board is not finished, and nothing is saved until everyone is across.
Read the banks
- Active time
- Crossings
- Not measured
- Hints
- Not measured
Round details
Matching the fewest possible means you found a shortest answer. It says nothing about you.
This is a puzzle. The crossings and the time are yours to beat and nothing else. They do not measure intelligence, reasoning or anything about you.
Explore the method
Learn to write a river crossing position down, and why the move that matters is the one that comes back.
On by default unless you turn it off. Saved choices are kept. Shares starts, completions, replays and error categories. For ChatGPT visits, starts and completions may include the first QuickenBrain page and country. No answers, drawings or names.
How this data is usedHelp
A river crossing puzzle gives you a boat with a few seats, a group of travelers, and a rule about who cannot be left alone together. You move everyone to the far bank.
Tap a traveler on the boat's own bank to put them in the boat. Tap one in the boat to put them back. Press Cross to sail, or tap one of the boat's oars. With the keyboard, Tab to a traveler and press Enter, then press C to cross.
Each board prints its own rules under the scene, where a round is played. They are checked when the boat lands, and whoever is in the boat counts as standing on the bank it touches. A crossing that would break a rule does not happen, and the line under the scene says who would be left in trouble.
Easy has six boards, Standard seven and Challenge nine. The levels group the number of travelers and the rules to plan around. New board moves to the next one at your level and asks first if your current board has been started.
The fewest is exact. A search runs over every position the board can reach and keeps the shortest way home from each one, so the number under the scene is a fact about the board rather than a guess. The same search answers the hint.
A hint makes the next move of a shortest answer for you and counts as a hint. A round played with a hint is still saved and still counts as finished, but it is left out of the community comparison, because a hinted round is not the same round as an unaided one.
A round is saved only when everyone is across. Leaving a board part way through, resetting it and taking a new board all save nothing. What is saved is the board, the crossings you made, the fewest possible, the hints and the time.
This is a puzzle. The crossings and the time are yours to beat and nothing else. They do not measure intelligence, reasoning or anything about you.
Every saved round is a finished one, so the statistics page shows your crossings and your solving time rather than an accuracy line.
The lesson behind this practice shows how to write a position down and what to look for. Read: Think in states
About this practice
Get everyone across in as few crossings or minutes as you can. Explore 22 boards with different rules and an exact minimum for each.
Learn a method
Think in statesReport a problem
On by default unless you turn it off. Saved choices are kept. Shares starts, completions, replays and error categories. For ChatGPT visits, starts and completions may include the first QuickenBrain page and country. No answers, drawings or names.
How this data is used