The kinematics of submarine landslides is important both for evaluating tsunami hazard potential as well as for evaluating hazards to seabed structures. This paper presents a kinematics analysis of a debris avalanche that was identified in deep water off the northwest coast of Sumatra. A numerical model is derived and used to investigate the relative influence of slide density, hydrodynamic drag, basal resistance, and hydroplaning. The model predicts a maximum slide velocity of 40-47 m/s. The slide density and shear strength of the sediments beneath the slide play a key role in the kinematics behavior.