This is a unique book that tells the story of a bunch of intrepid and inspired men who pioneered the exploration of the last great unknown: the deeps of the sea. How would you fancy wading out under water with nothing more than an inverted coal bucket over your head? Would you agree to a fight a shark, equipped with nothing more than a knife, all so that some movie company could film the gory encounter? Inventive, adventurous, foolhardy to the point of recklessness, many of the diving pioneers were also world-famous in their own right, like the great biologist JBS Haldane, who worked out how to survive at dangerous depths. Others evolved from treasure seekers to become the first underwater archaeologists, exploring ancient shipwrecks in exotic waters, or, most interesting of all, opening our eyes to the beauty of marine habits and wildlife, including the seriously threatened coral reefs. The author, himself a marine biologist and diver, blends all this into a magical weave of fact and wonder enlivened by a mordant wit and a delightful eye for quirky detail. I would recommend it to any reader.