In this study, we investigated cause-specific temporal and spatial trends in sea turtle strandings in New Caledonia. Five species of sea turtles were recorded in the 406 strandings documented between January 1999 and March 2021. Green turtles represented the majority of the stranded species (68%), reflecting the importance of the resident green turtle population in New Caledonian waters. Nearly half of the individuals stranded were juveniles (48%). The great majority of strandings were recorded in the South Province, the most populous province of New Caledonia (73%). The main causes of the strandings were classified as unknown (50%), followed by poaching (17%), by-catch (15%), collision (10%), natural (8%), plastic ingestion (0.5%) and other (0.5%). This study contains the first official record of the presence and relative importance of fibropapilloma in New Caledonia, but we could not determine if it was the cause of death for the stranded individuals. Two individuals, after necropsies, were found to have ingested plastic (one in 2011 and the other in 2020). This is the first record of plastic ingestion for sea turtles in New Caledonia. Three significant trends were also found during the study: an increase in the number of individuals reported in the study since 2004; a seasonal effect, with most strandings occurring in summer (November to January); and stranding hotspots. Rehabilitation allowed for 35% of individuals found alive to be released back into the wild. This study suggests that mitigation strategies such as “go slow” zones and a robust stranding network should be put in place in New Caledonia.