Compaction-driven and buoyancy-driven fluid flow are the major driving forces in submarine basins; however, the impact of coupling these driving forces has yet to be fully evaluated. This is the first analysis to couple the transient interactions of compaction-driven and buoyancy-driven flow in oceanic sedimentary basins. We use finite element modeling to explore the effects of sediment compaction overlying a permeable oceanic crust layer where free convection occurs. Four numerical experiments examine the parameter space where each driving force dominates the flow field. In higher-permeability crust (k > 10-13 m2) buoyancy-driven flow dominates the fluid flow patterns in the basin, though compaction does cause minor alterations to fluid velocities and convection cell evolution. Compaction dominates the system when low permeability crust inhibits free convection (k < 10-15 m2) and can stimulate fluid flow in the oceanic crust by directing fluid from sediment pore spaces downward into the crust, possibly rejuvenating flow in older, lower-permeability submarine environments. In mixed-flow systems (k ~ 10-15 to 10-13 m2) both forces are approximately equal in importance and both contribute to the development of flow patterns. Fluid from the sediment layer is expelled downward into the permeable crust, which modifies the fluid flowlines. Instead of convection cells, a flow-through pattern forms in which all fluid is transported laterally across the basin. This increase in lateral transport could have significant implications for geochemical mass transport in submarine environments. Though flow rates are relatively small (~mm/yr), low-velocity fluid flow can be important in geochemical, mechanical, biological, and hydrogeologic systems.