Coastguard and lifeboat crews are searching Lough Derg after a damaged speedboat was found upturned in the water last night.
The alarm was raised in the Youghal Bay area of the lake at around 9:20pm when the vessel was spotted in the Youghal Bay area of the lake close to Garrykennedy on the Tipperary side.
The owner of the boat has been identified but has not been located.
No-one has been reported missing in the area.
Coastguard and lifeboat vessels began searching again at 5am this morning while a shoreline search is to be carried out.
A helicopter is also due to join the operation.
Garda and navy divers have also been asked to help out and a local dive unit will be in the water later.
Jim Guirey is Station Officer with Valentia Coastguard.