This paper presents optimization studies on the dimensions of a gravity-based wave energy converter foundation. The wave energy converter is based on a linear driven generator mounted on a gravity-based foundation located at the seabed. The generator is connected to a point absorbing buoy on the sea surface via a rope. Such a device, developed at Uppsala University, has been in operation on the Swedish west coast since 2006. The optimization is focused on the undesirable motion of the gravity-based foundation, particularly the study of the tip and lift phenomena regarding the heave and surge forces. Heave and surge forces are calculated from the interaction between the waves and the floating buoy. The results with respect to the foundation of a new generation wave energy converter show that the dimensions of the foundation can be reasonably optimized with the presented methodology. The optimization is intended to estimate the appropriate dimensions for the gravity-based foundation with respect to the specific wave climates at the test site. Therefore, one can avoid unnecessary construction costs and promote the competitiveness of the whole wave energy converter.