A model test program to study the dynamic behavior of two deep water Spar platform concepts was conducted in a large model basin. One design, now referred to as the classic spar, had a solid cylindrical external hull with an internal moonpool extending the length of the hull. It was kept on station using a spread mooring system. The second design was a single tether spar which also utilized a spread mooring system. This design had a smaller hull and did not have a moonpool. For the data presented, the spar platforms were allowed six degrees of motion which then couples the wave runup measurements to the platform motion characteristics. The experimental data was characterized using statistical methods and power spectral density functions. A two parameter empirical model was developed for estimating wave runup in random seas.