Ten people were rescued from a speed boat on the River Shannon late last night.
The boat was on a dark stretch of the river close to Fort Henry and about 2kms south of Killaloe when it began to take on water.
Two people jumped off the boat and swum ashore.
Killaloe Coast Guard's rescue boat took the 10 remaining passengers to safety and the speed boat was towed to Ballina.
The Shannon-based Coast Guard helicopter was put on standby, but was not needed.
The Killaloe Coast Guard has appealed to boat owners not to navigate at night.
A Killaloe Coast Guard spokesperson said: 'There is no doubt but 10 lives were saved last night. This could easily have been a tragedy. Lough Derg is not for night navigation and it was only the quick response of our volunteers that prevented a far more serious incident.'
