Mantle plumes are buoyant upwellings rising from the Earth’s core-mantle boundary to its surface, generating hotspot chains that track the direction of plate motion. Eastern Australia contains three contemporaneous volcanic chains (1 onshore, 2 offshore) that have long been held to be formed by three separate plumes, however, this fails to explain their geochemical similarity and close spacing. Surrounding these plume-related volcanoes are hundreds of smaller volcanic edifices which exhibit no correlation with plate motion. Armed with numerical models of mantle convection, plate reconstructions, seismic tomography, and geochemistry of eruption products, we aim untangle the complex history of volcanism in eastern Australia and offshore. In this talk, I will discuss how plume-slab interaction can lead to plume branching, potentially forming parallel hotspot chains, and the influence of slab flux on driving non-age progressive volcanism.