Aquarium

A pure-logic water puzzle. The grid is divided into tanks, and water in each tank always settles to one flat level. Use the row and column clues to work out exactly how full each tank is. Every board has a single solution reached by deduction alone. How fast can you fill them?

How to play

The grid is carved into tanks, marked by the thick borders. Because a tank is one sealed container, water poured into it always rises to a single flat level: every cell at that level or below holds water, and everything above it is air. A tank can be empty, full, or filled to any level in between.

Around the edges are the clues. The number to the left of a row tells you how many of that row's cells are water; the number above a column does the same for that column. Your job is to choose a water level for every tank so that all of those counts come out exactly right.

Tap a cell to cycle it through water, a blocked marker (a handy way to note cells you have ruled out), and empty again. Work from the clues: a row needing zero water forces every tank touching it to stay below that row, while a full row floods them. There is always exactly one solution, reachable by logic with no guessing. Your time is your score — solve it quickly and tap New for a fresh board.

Tips & strategy

Start with the extreme clues. A row or column whose clue is 0 has no water at all, so every tank cell in it is air — and that often forces those tanks to sit lower elsewhere. A clue equal to the full width means the whole line is water. These give you free, certain cells to build from.

Remember water falls, never floats. Within one tank, if a cell is water then every cell of that tank below it must be water too, and if a cell is air then every tank cell above it is air. Marking one cell often cascades up or down its tank immediately.

Use blocked markers to track 'definitely air'. When a clue proves a cell can't be water, mark it blocked. Those X's stop you re-checking the same cells and make the remaining levels much easier to read.

Count what's left in a line. If a row needs three water cells and two are already placed, exactly one of the remaining tank-cells in that row is water — and the falls-not-floats rule usually pins down which tank it belongs to.