Why it was made

Work out what's beneath the surface

In Sonarium, each number tells you how far away the nearest hidden target is. Use those distances to work out the shape, one square at a time. Finishing a board reveals a creature or wreck and adds it to your Field Guide.

Later puzzles introduce new rules, including a reading that must be identified as false. A daily puzzle gives everyone the same board to solve. The game is available for iPhone in English and Traditional Chinese; the opening seas are free, with a purchase to unlock the rest.