More than 60 divers will enter Lough Ree, Co Roscommon, today on the third day of a search for a Swiss man who is presumed dead after a boating accident in which his wife drowned.
The divers will search in dark water over 30 metres deep for the body of Mr Walter Borner (71), who lived at Dorf, one hour from Zurich.
The body of Mr Borner's wife, Ruth, was discovered near Lecarrow on Monday evening, sparking a search for her husband. The couple's boat, Winkleried, was discovered on Tuesday after being grounded on Inchmore island with the engine still running.
An Air Corps helicopter joined the search yesterday evening. Although the circumstances of the deaths may never be established, one theory is that one of the couple fell overboard and the other went to their aid.
Mrs Borner was not wearing a lifejacket when she was found, and lifejackets were found on the cruiser. This has heightened speculation that whatever caused their deaths was a sudden development during their cruising trip.
They had an intimate knowledge of the Shannon, having cruised it for up to four weeks every year for the past 30 years. It has also emerged that the couple were due to return to Switzerland on Tuesday evening.
Volunteers from Lough Ree and Athlone Sub-Aqua Club conducted searches yesterday, and they will be joined today by other volunteer divers from Dolphins SAC, Roscommon; Banagher SAC, and Longford Scuba Diving Club.
"We have been concentrating on the area known as Lecarrow, near Warrenpoint.
"Visibility would be considered good," said Mr Thomas McGlynn, chairman of Lough Ree SAC.
It is likely they will be focusing more on the Inchmore island area today, where the water is so dark "you can barely see your hand". The water around Inchmore island is about 30 metres deep in parts. Gardaí have appealed for information from fishermen or tourists who may have noticed the couple on their cruiser on Sunday or Monday.