The thermally driven large-scale ocean circulation is studied. We obtain a steady state ocean circulation by running the time-dependent, nonlinear model to equilibrium using restoring boundary conditions on surface temperature. This is simulated by MITgcm using a 2◦ × 2◦ spherical polar grid. We examine how this circulation relates to theories of the surface - and the abyssal circulation. These theories include the linear thermocline theory and Stommel and Arons theory. An important factor in returning the deep water to the surface, is the diapycnal mixing. Why this is important will be discussed. The reasons why and where the deep water upwells, are well debated. We find that positive vertical velocity mainly occurs at the western boundaries, where both the currents in the abyss and at the surface are strong. The simulated ocean circulation contains many of the observed currents in the world, like the Antarctic Circumpolar Current (ACC), the Kuroshio Current, the Agulhas Current and the Gulf Stream. In addition, the meridional overturning has a realistic strength.