In the frame
A slender reef shark with a pale belly cruises along a steep wall of coral and sponges. Orange sea fans and round coral heads cover the wall on the right; the left half is deep blue open water.
This dive turns the picture into a 4 × 4 slide puzzle: 15 tiles and one empty space. The shuffle is fixed, so everyone starts from the same board, and it is always solvable.
Dive plan
- Start with the easy part: the shark and the orange sea fans on the wall.
- Save for last: the open blue water. About 40% of the frame has little detail, mostly on the left side, and those pieces look alike.
- Finish the top row first, then the left column; the puzzle shrinks to a smaller board each time.
- Switch on the numbers if two tiles look alike — they show where each tile belongs.
- Look-alike tiles are where the numbers help most: plain water or sand gives few clues about order.
- On a 4 × 4 board, leave finished rows alone and work only in the rest of the board.
Colours of the picture
Main colours, measured from the picture's pixels: charcoal (27%), deep blue (27%), brown (20%) and slate grey (16%).
- charcoal27%
- deep blue27%
- brown20%
- slate grey16%
- teal10%
How deep it goes
Depth 2 of 5 — an easy dive.
Reef dives sit in the middle: enough pieces to need a plan, never so many that a phone screen feels crowded.