Carbon monoxide (CO) is a colorless and odorless gas generated from the incomplete combustion of hydrocarbon-based fuels. Medical research has shown that human exposure to elevated concentrations of CO can cause serious injury or death. Of increasing concern are CO-related poisonings and fatalities associated with the use of recreational watercraft. Currently there is a lack of awareness of this health hazard among the general public. This presentation summarizes the risks and dangers recreational watercraft users may face from carbon monoxide exposure.