Our seas are host to an extraordinary variety of plant and animal life, but much of it remains mysterious and great imagery is surprisingly hard to find. Alex Mustard is one of the world's leading underwater photographers and his images are so crisp and immediate that the animals seem to swim out of the water towards you. This beautiful book gathers together a selection of his award-winning images and a number of new ones to create a vivid picture of the seas and oceans and the animals that inhabit them, each chapter accompanied by a 1500 word essay and extended captions written by leading natural history writer, Professor Callum Roberts.

The text addresses the issue of change in the oceans along with tales of oceanography, marine life and human history in the seas and aims to help the reader to get to know the oceans, understand how marine animals live their lives and how they have, are and may well adapt to change.

Alex Mustard has been taking underwater photographs for 30 years. In 2013 he was named European Wildlife Photographer of the Year and was a category winner in the UK Natural History Museum Wildlife Photographer of the Year competition. His last book, Reefs Revealed, won the International Grand Prize for the best book of underwater photographs.

Callum Roberts is Professor of Marine Conservation at the University of York in the UK and is author of two award winning books, The Unnatural History of the Sea and Ocean of Life: How our Seas are Changing. For the last 25 years he has used science to make the case for stronger protection for marine life at both national and international levels.