Fill each aquarium with water so that every row and column hint is satisfied.
Coral marks water, ✕ marks a cell you are sure is empty. Thick borders separate aquariums.
Tip
Baddeley and Hitch (1974) proposed visuospatial working memory as the key resource for spatial-relation reasoning. Cornoldi and Vecchi (2003) documented the value of multi-constraint visuospatial puzzles for working-memory training, and Shah and Miyake (1996) showed that spatial processing resources are separable from verbal resources, making training effects domain-specific.