The tropical Pacific Ocean is a climatically import region as it is the atmosphere's largest source of oceanic CO2 and generates 20-30% of global primary productivity that support many local fisheries. The nutrient and oxygen-rich Equatorial Undercurrent regulates the tropical Pacific’s high primary productivity, oxygen minimum zones and the cycling of carbon. As such future changes to tropical Pacific circulation have the potential to impact local ecosystems, commercial fisheries and the global uptake of carbon. While studies report conflicting projected changes of the tropical Pacific oxygen minimum zones, it is suggested that changes depend on a balance between the compensating effects of Equatorial Undercurrent transport and biological activity. Studies project robust changes of the Equatorial Undercurrent and its low latitude western boundary sources, however, the changes to the Equatorial Undercurrent water sources, pathways and evolution requires further examination. Here, we investigate how and why the Equatorial Undercurrent sources and pathways are projected to change in a future of increasing greenhouse emissions. We discuss sensitivity experiments, hindcasts and future changes of Equatorial Undercurrent water transport using Lagrangian particles. The particles are advected in the eddy-resolving Ocean Forecasting Australia Model version 3 (OFAM3), which is a downscaling run under the RCP8.5 emission scenario.