A marine wet exhaust system (10) which injects water into the exhaust flow for cooling and attenuating noise includes a particulate capture and containment system (14) for removing particulates and fluid contaminants from the exhaust gas and the waste cooling water of the discharge. With a first embodiment, this is accomplished by separating the waste cooling water and entrained particulates from the exhaust gas in a muffler/separator (12); accumulating the waste cooling water and entrained particulates in a reservoir (52); and separating the entrained particulates from the waste cooling water in a filter (50). The system further includes a reservoir discharge pump assembly (54), a reservoir drain line (86) and a bleed line (74) to maintain water levels in the reservoir and the filter. With a second embodiment, a condensate trap (56) separates particulates and condensates from the de-watered exhaust gas and returns them to the reservoir (52).