Two young men were taken to hospital after the boat they were on hit the rocks in the limits of Cirkewwa and overturned, the police said.
The accident took place at 5am.
Members of the Civil Protection Department were called on site to assist the two men, aged 19 and 20, both residents of Mellieha.
Both were taken to hospital for treatment, with the 20-year-old suffering serious injuries while the teenager is still to be certified.