The Indo-Pacific Maritime Continent (MC) is the home to the strongest atmospheric convection center and the most active interaction between the troposphere and stratosphere on Earth. It also hosts the only oceanic pathway from the tropical Pacific and Indian Oceans. The complex distributions of land, topography and water in this region present a great challenge to observe, understand and predict processes and variability in its atmosphere, ocean, and their interaction. Among many outstanding issues related to the MC, its barrier effect on propagation of the Madden-Julian Oscillation (MJO) is critical to prediction of the life cycle of the MJO and its global impact. Understanding the barrier effect is still at its infant stage. Testing and advancing proposed ideas for explaining the barrier effect require innovative approaches using high-resolution numerical models and observations. The ongoing international program Years of the Maritime Continent (YMC) is collecting data and fostering collaborations that hopefully would lead to breakthrough in the study of the MC problems.