Bystanders who drown during a rescue attempt in aquatic waterways are becoming an increasingly important issue within drowning prevention. In the Australian context, the majority of these incidents occur in coastal water ways. This study documents and characterizes bystander rescuer fatalities within Australian coastal waterways that occurred between 1 July 2004 and 30 June 2019 in order to provide suggestions for future public safety interventions involving bystander rescuers. Data was sourced through Surf Life Saving Australia’s (SLSA) Coastal Fatality Database, which collates information from multiple sources. Sixty-seven bystander rescuer fatalities in coastal waterways were reported during the 15-year period, an average of 4.5 per year, which is a significant proportion of the five fatalities previously reported across all Australian waterways. The majority of coastal bystander rescuer fatality incidents occurred in the state of New South Wales (49%), at beaches (64%), in regional or remote areas (71%), more than 1 km from the nearest lifesaving service (78%), during summer (45%), in the afternoon (72%), in the presence of rip currents (73%), and did not involve the use of flotation devices to assist rescue (97%). The majority of coastal bystander rescuer victims were Australian residents (88%) born in Australia/Oceania (68%), males (81%), aged between 30–44 years old (36%), visitors to the location (55%), either family (69%) or friends (15%) of the rescuee(s), and were attempting to rescue someone younger than 18 years old (64%). Our results suggest future safety intervention approaches should target males, parents and carers visiting beach locations in regional locations during holiday times and should focus on the importance of flotation devices when enacting a rescue and further educating visitors about the rip current hazard. Future research should examine the psychology of bystander rescue situations and evaluate the effectiveness of different safety intervention approaches.