This book provides a comprehensive review of UV radiation effects in the marine environment. A multidisciplinary approach is adopted to discuss all aspects from a physical, chemical and biological perspective. The book begins by describing the attenuation of UV radiation in the atmosphere and sea water, outlining the photochemical reactions involved and highlighting the role that such chemistry can play in influencing the biogeochemical cycling of various elements. The deleterious consequences of such radiation on organisms and strategies adopted to mitigate these harmful repercussions are discussed. The organisms considered range from virus and bacteria through phytoplankton and zooplankton to fish and mammals. The book is aimed at researchers and graduate students in photobiology, photochemistry and environmental science. It will also be useful as a supplementary text for courses in oceanography, climatology and ecology.