Diagonal lines in images are essentially straight lines that are formed from the image content and that run from one corner of the image to the opposite corner or to an object in the image. In the above image the tree is included in the diagonal line. Diagonal lines are often useful if objects are included on the diagonal lines it can give the image a sensation of sliding and moving. The diagonal line can be a most dynamic type of composition.
The diagonal lines in the image above, are represented by the joining of the land and the sea leads from the lower right corner of the image to the trees on the diagonal line on the left side of the image. Another line is represented by the joining of the sky and the sea in a similar way.