In order for legged robotic platforms to become adept enough to operate in unstructured, outdoor environments it is critical that they have the ability to adapt to a variety of terrains. One class of terrains to consider are regions of shallow, dense fluids, such as a beach-head, stream banks, snow or mud. This work examines the behavior of a simulated SLIP runner operating in such a viscous medium. Simulation results show that intelligently retracting the leg during flight can have a profound effect on the maximum achievable velocity of the runner, the stability of the resulting gait, and the cost of transport of the runner. Results also show that trudging gaits, in which the leg is positioned behind the center of mass, can be favorable in certain situations in terms of energy consumption and forward velocity.