Different subjects such as kelp in a current can lend themselves to be photographed as diagonal lines. Diagonal lines can work to draw the viewer ’s eye through a photo to the main subject and can also create points of interest where they intersect.

Some studies have shown people view images from left to right. This makes a diagonal from lower left to upper right a useful tool to create interest in a photo. Diagonals seem to work best when they are off center as opposed to corner to corner. Multiple diagonals can create interest but too many can create chaos.