The aim this dissertation was to examine the interactions between exercise before and SCUBA diving. The impact was determined on variables beyond VGE, which traditionally have served as a surrogate marker for decompression stress, but alone are a poor indicator of DCS risk. Four dive studies were conducted for this investigation, three on exercise before diving and one on exercise after diving. In addition to VGE, outcomes to assess decompression stress included arterialization of gas bubbles; changes in circulating MP counts, MP subtype expression associated with the inflammatory response, platelet counts and activation, and endothelial function. Exercise before diving was already considered by some to be a protective form of preconditioning, however, this conclusion was primarily based on VGE analysis. These studies demonstrate a mitigation of MP counts and platelet-neutrophil activation and interaction that is associated with protective benefits in the murine model, providing additional information on the mechanism beyond VGE analysis. This effect was observed with both aerobic running and anaerobic cycling and was more pronounced following the running. Exercise after diving led to an increased incidence of arterialization compared to resting conditions. Arterialization during exercise was preventable with concurrent 100% O2 breathing and, arterialization while breathing atmospheric air ceased almost immediately after exercise was terminated. This may also demonstrate one of the mechanisms responsible for the positive outcomes associated with O2 breathing as a first aid treatment for DCS. The intensity at which this arterialization occurred is variable with each individual. In some individuals the simple task of surface swimming or carrying equipment after a dive may be intense enough to cross the arterialization threshold. From this study it was demonstrated that exercise after diving can provoke arterialization, which is associated with an increased relative risk of DCS. Exercise timed two hours before diving does not seem to impact VGE to a significant degree, however, it mitigates MP counts and certain indicators of the inflammatory process which are correlated with DCS in mice. MPs are also believed to contribute to the pathogenic process of certain diseases. Some of these findings may be useful immediately; those related to exercise after diving. Other findings provide more information towards uncovering an accurate understanding of the pathogenesis of DCS as well as mechanisms that may help protect against it.