Directional lines (horizontal, vertical, and diagonal): there are strong diagonal lines in the composition. The lines of the raft form a base as an implied diamond shape on which the drama unfolds. This is countered by the mast and rigging.
Value is one of the seven elements of art. Value deals with the lightness or darkness of a color. Since we see objects and understand objects because of how dark or light they are, value is incredible important to art.