INTRODUCTION: Recently, an analysis of Canadian seaplane accidents terminating in water (1995-2019) was conducted, but ultralight water accidents were excluded due to differences from general aviation operations. This is the first literature that reports a series of ultralight accidents that occurred in water. The purpose of this paper is to identify the circumstances surrounding ultralight water accidents in Canada and to identify actions with the potential to improve survival. METHODS: Ultralight water accidents that were reported to the Transportation Safety Board of Canada between 1990 and 2020 were reviewed. RESULTS: Of the 1021 accidents that involved ultralights, 114 terminated in water, involving 155 occupants and 8 fatalities, yielding an occupant mortality rate of 5%. Of the accidents, 52% occurred during landing. There was less than 15 s warning in 78% of cases, which included five (63%) fatalities. The aircraft inverted in 40% of the accidents and, in 21%, it sank immediately. Loss of control was the terminal cause of the accident in 43% of cases, while adverse environmental conditions were reported in 38% of accidents. Little or no details were included on lifejacket or restraint harness use, status of emergency exits, water temperature, or occupant diving experience or underwater escape training. CONCLUSIONS: The mortality rate in ultralight aircraft water accidents was less than half that of helicopter and seaplane ditchings, but the lack of warning time was similar. All pilots and passengers need to have a well-practiced survival schema before strapping in and can benefit from underwater escape training. MacDonald C, Brooks C, McGowan R, Rosberg A. Canadian ultralight accidents in water (1990 to 2020) . Aerosp Med Hum Perform. 2023; 94(6):437-443.