Photoinhibition under solar radiation was measured in several green, red, and brown macroalgae harvested from different depths using pulse amplitude modulation (PAM) fluorescence on site in Cabo de Gata (South East Spain). Photosynthetic quantum yield decreased after exposure to unfiltered solar radiation and recovered during subsequent shade exposure. Surface algae were inhibited but recovery was fast and complete within a few hours. In contrast, inhibition in deep water algae were even more pronounced, and recovery was incomplete or non-existent. Photosynthetic quantum yield was determined from dawn to dusk at 1 h intervals in algae immediately after harvest. Photoinhibition occurs in all algae even at their natural habitat when the sun is at high angles. Similarly, photoinhibition was found during noon hours in algae harvested from deep water and exposed at 2 m depth.