The human population of the planet is projected to peak at nearly 10 billion by late 2050s and settle at about 9 billion by 2100. For reference, the current population is 7.7 billion. The population growth will lead to significant burden on the water-energy-food nexus. It is envisioned that the so-called `blue-economy’ will increasingly contribute to the water-energy-food nexus over the coming decades and help sustain the population of the planet. The term `Blue economy (BE)’ represents a new perspective in commercial enterprise in maritime -- encompassing coastal, littoral and blue water – environment. Irrespective of the precise definition of the term blue-economy, its success depends upon intricate synergy between science, technology, ecology, economics, ethics and international policy. The talk will present a possible roadmap to rapidly develop and fully utilize the benefits of BE while being responsible stewards of the oceans. To engineer the blue economy, we need a new set of skills and tools. We present the concept of an Ocean Expert System which will not only enable us to engineer BE but also help make prudent choices that lead to safe, scalable and sustainable economy. The three main components of the expert system are: Ocean Data Repository, Integrated Digital Twins and Holistic Decision Dash Board. The details of these components and a possible transition strategy toward blue economy will be presented. A key component of this is retraining current off-shore workforce and retooling/adapting many of the current off-shore assets. While many uncertainties lay ahead, there is reason for much optimism provided bold, prudent and visionary actions to be taken in a timely manner.