This 3rd EOS Topical Meeting on Blue Photonics® - Optics in the Sea (Blue Photonics 3), to be held at the Royal Netherlands Institute for Sea Research (NIOZ), Texel, Netherlands, will provide a major international forum for the discussion of marine optics and its applications. Its aims are to review recent progress in the field, to promote the formation of a community of scientists and engineers working in related areas, and to stimulate the interdisciplinary collaboration required to meet the rapidly developing challenges of the future.