Tactical Combat Casualty Care (TCCC) has always emphasized the need to consider the tactical setting in developing a plan to care for wounded unit members while still on the battlefield. The TCCC Guidelines provide an evidence-based trauma care approach to specific injuries that may occur in combat. However, they do not address what modifications might need to be made to the basic TCCC guidelines due to the specific tactical setting in which the scenario occurs. The scenario presented below depicts a combat swimmer operation in which a unit member is shot while in the water. The unit casualty response plan for a combat swimmer who sustains a gunshot wound to the chest while on a mission is complicated by the inability to perform indicated medical interventions for the casualty while he is in the water. It is also complicated by the potential for ballistic damage to his underwater breathing apparatus and the need to remain submerged after wounding for at least for a period of time to avoid further hostile fire. Additionally, there is a potential for a cerebral arterial gas embolism (CAGE) and/or a tension pneumothorax to develop while surfacing because of the decreasing ambient pressure on ascent. The tactical response may be complicated by limited communications between the mission personnel while submerged and by the vulnerability of the mission personnel to antiswimmer measures if their presence is compromised.