An Introduction to Biological Oceanography is completely revised and updated based on the prior edition by Carol M. Lalli and Timothy Parsons. This revision aims to provide scientific understanding of how biological processes in the ocean work and how they are affected by physical, chemical and geological processes. This understanding is foundational for humans to assess our impact on the oceans, how to best implement conservation and management practices and ultimately, ensure sustainability of the many ways humans depend on the ocean. A rich tapestry of images supports the text, including data figures, info-graphics and artistic renditions. Since the book was last published, major new discoveries, including a new domain of life and global human impacts that change the oceans and biosphere have required a revision and amendment of the prior edition. However, many themes in this book remain timeless, such as the interactions of light with water and the importance and beauty of species diversity. A major theme is to develop intuition and predictive skills to relate environmental conditions with biological processes and structures, such as production and food webs across seasons or latitudes. This volume is designed so that it can be read on its own. The science of oceanography as a whole is multidisciplinary, and early chapters include fundamental principles in physics, chemistry and geology to highlight how underlying mechanisms constrain biological processes in the ocean. For the same reason, there is also some basic biology, particularly ecology covered.