A second teenage boy has died after getting into difficulty in Lough Swilly.
One teenager remains in serious condition in hospital, while a third's body was recovered from the water yesterday afternoon.
The Coast Guard were alerted to a report of three teenagers in difficulty in the water at around 4pm.
One teenager managed to swim to safety, while another was rescued.
Both were brought to Letterkenny University Hospital in a serious condition.
This morning, the boy rescued from the water has died in hospital.
A third adult teenager's body was recovered last night, and a post-mortem is due to take place
Gardaí say investigations are ongoing.