Airborne Lidar Bathymetry (ALB) waveforms provide a time log for the interaction of the laser pulse with the environment (water surface, water column and seafloor) along its ray-path geometry. Using the water surface return and the bottom return, it is possible to calculate the water depth. In addition to bathymetry, the ALB bottom return can provide information on seafloor characteristics. The main environmental factors that contribute to the ALB bottom return measurements are: slope, roughness, vegetation, and mineral composition of the surface geology. Both the environment and the ALB hardware affect the bottom return and contribute to the measurement uncertainties. In this study, the ALB bottom return waveform was investigated spatially (i.e., area contributing to the return) and temporally (i.e. the shape of the waveform return) for seafloor characterization. A system-agnostic approach was developed in order to distinguish between the spatial variations of different bottom characteristics. An empirical comparison of bottom characteristics was conducted near the Merrimack River Embayment, Gulf of Maine, USA. The study results showed a good correlation to acoustic backscatter collected over the same area.