The cool temperate waters around Britain and Ireland are at a cross­roads between warmer waters to the south and Arctic ones to the north. Consequently they contain a huge variety of marine animals and plants which differ significantly from place to place around the islands and shores.

This guide aims to introduce divers and snorkellers to the most common and identifiable animals and plants they will encounter underwater, both widely distributed species and some of the specialities of different areas.

Completely revised and expanded this Second Edition covers almost 300 individual species and groups of species seen underwater, from tiny fragile sea spiders to the massive plankton­feeding Basking Shark.

● 265 individual species descriptions, each with information on habitat, size, depth range and distribution in easy to use icon format
● Text emphasising the key features for identification of each species and possible confusions
● Underwater photographs showing each species as the diver or snorkeller would see it
● A unique ‘confidence guide’ to identify which species are easily recognised and which are likely to require confirmation
● Over 30 additional groups of plants and animals that cannot be identified individually underwater, but can be important features of the living community
● Information on marine habitats, conservation status and non­native species in British and Irish waters

This guide complements the other titles in this series by providing an introduction to a wide range of species, which can be followed up by referring to the greater detail available in the specialist guides.

Julie Hatcher is a marine biologist working in marine conservation in Dorset. Her work involves raising awareness of the marine environment and marine and coastal wildlife in the UK. She has written many articles for newspapers and magazines, as well as designing interpretation panels, posters and leaflets. She also leads guided rockpool rambles and seashore identification training courses and has been a scuba diver for many years, mostly in the UK.

Steve Trewhella is a diver and photographer, specialising in the photography of British marine life above and below the waves. He is also a keen naturalist with a particular interest in the coast and sea. When not diving he enjoys rockpooling, beachcombing and recording some of the more obscure marine and coastal species found in the British Isles. His images are used in publications all over the world and he has worked as a contributor on many natural history television features.

Julie and Steve met in 2004 since when they have organised projects to record strandline invertebrates and intertidal snapping prawns as well as carrying out dive surveys on seahorses and stalked jellyfish in their local area. They married in 2013 and live on the Isle of Purbeck in Dorset.