Man is a terrestrial animal. Because of this, he does not have a direct perception of the marine realm as it is the case for the terrestrial environments neither his sensorial apparatus is particularly suited for observing the ocean. Technological development is progressively helping in overcoming those limits and the resulting scenario is reinforcing the leading role played by microscopic biota. The ocean microbiome, i.e., the plankton, is among the least known component of the Earth system. It is a typical complex system with multiple, poorly know interactions continuously reshuffled by the motion of the fluid. In the pelagic environment the habitat is not fixed in space and the niche construction by biota is still elusive, if any exists. All the above makes the management, the sustainable exploitation, the prediction on the duration of the ecosystems services provided by the sea, of which plankton is the pillar, quite difficult. By contrast, future societal economic growth is more and more projected on the use of the sea, which implies also the prevention and the solution of conflicts for competing uses which demands for a holistic approach integrating ‘natural’ and ‘social’ sciences. The sea is becoming a crucial test case for the capability of modern societies to regulate their functioning and to properly educate the new generations. Seas and oceans represent one of the most complex systems in terms of environment, human activities, regulation, governance, industrial sectors, geo-political scenarios.