We are well into the tropics now. The sea around us is the deep blue of the open ocean, far from land. The surface is broken by whitecaps blown by the southern trade winds. Day by day, we are traversing great regions of the Atlantic, feeling our planet moving around us as we make our way slowly north. It’s a remarkable place to be – the sea stretches out to the horizon all around us, featureless to a casual glance, but offering a beautiful insight into the real nature of our world: Planet Ocean.