Think spot the difference puzzles are easy? Look again. With 38 glorious images to compare, Extreme Spot the Difference is one of the toughest, most enjoyable puzzle books ever published. Each carefully chosen, high-resolution photographic vista has been cunningly modified with no fewer than 50 ingenious changes. The images feature a variety of subjects, from cityscapes and amusement parks to starry skies and sailboats in the sea.