This paper evaluates marine X-band radar's capability to retrieve interior ocean properties from internal wave (IW) sea surface signatures. In particular, we study the link between the wave-induced backscatter intensity modulation and the IW amplitude as well as the surface velocity convergence (and divergence). The radar measurements were complemented by shipborne ADCP and microstructure profiler measurements. This study's focus lies on data that were collected during the 12-hour tracking of a particularly energetic wave, with peak amplitudes above 20 m. Results indicate that hydrodynamic surface roughness modulation is the dominant backscatter mechanism. In addition, we show that the IW-induced radar backscatter intensity modulation correlates with both peak surface velocity gradients and IW amplitudes.