Seagrass Posidonia oceanica, or Posidonia, is an endemic species of the Mediterranean Sea that forms vast meadows and provides numerous ecological services. Posidonia is an Angiospermae, indicating its capacity to undergo flowering, similar to other terrestrial plant species. Nevertheless, the flowering of Posidonia is infrequent, with its primary mode of reproduction being vegetative. It is believed that the occurrence of Posidonia blooms is most often caused by environmental stress (such as high temperatures, limited light availability, and pollution). These stressors stimulate the organism to enhance genetic variety to increase resilience. Mass flowering events in the Mediterranean Sea were recorded in 1971, 1982, 1993, and 2003, indicating a recurring pattern of 10–11 years. In November 2021, Posidonia flowering was recorded in the waters of the island of Silba. The meadow flowering frequency was 7,7 ± 0,625 % shoots at 4 m depth and 5,96 ± 1,46 % shoots at 10 m depth. These results fall within the expected range of typical flowering frequencies. A notable disparity was seen in the flowering intensity between the depths of 4 m (67,5 ± 6,17 inflorescences per m²) and 10 m (28,75 ± 5,03 inflorescences per m²). The flowering frequency and intensity increased with increasing temperature. Low reproductive success was found at 4 m depth (3,25 ± 2,18 %), while at 10 m depth, not a single inflorescence produced fruit (reproductive success 0 %). The occurrence of reduced flowering success may be attributed to internal variables that have contributed to fruit abortion.