“Knowledge of the oceans is more than a matter of curiosity. Our very survival may hinge upon it.” – President John F. Kennedy, March 1961

It has been famously stated that we know more about the surface of the Moon than our oceans, and yet it is becoming ever more vital that we deepen our understanding of the importance of life in our seas: We are locked in a race against ourselves to learn about the environment that covers 70 percent of the planet, before we destroy it. Thankfully, there are plenty of people out there doing just that.

From adventurous technical dives that uncover vast, unexpected ecosystems, to scientific dives from which divers return with knowledge of new species, to hard-core explorations of freshwater systems, these pages are full of inspiring tales of discovery.

But you don’t need to head to 70 metres, or have a PhD, to discover exciting new elements of the underwater world. One of the most wonderful things about diving is that you can find something that is new to you every time you descend, if you know what you’re looking at.

The oceans are vast, diverse, and fascinating, and a little education can go a long way to enriching the experience. Even a dive site that you think you know well will offer up startling secrets if you look in the right places...