The father (45) and his son, from Upper Austria, were out in a catamaran on Tuesday which capsized near Podersdorf. They were able to climb back onto the boat but the teenager then jumped overboard to untangle a rope, and was swept away by a large wave.
His father threw him a lifebuoy but was unable to catch hold of him and then lost sight of his son. He then made a distress call and was soon picked up by a rescue team. There has been no sign of his son since Tuesday.
"The situation is unchanged," police spokesman Wolfgang Bachkönig told the ORF. He said that police teams will be discussing whether to search the shores of the lake with sniffer dogs. They have already searched the lake with thermal imaging cameras.
The search has been more difficult because “the area where the boy went missing is the deepest part of the lake - almost two metres - so not the shallow part of Lake Neusiedl,” a spokesman from the fire department said. The water is also very cold, around 13 degrees.
Lake Neusiedl straddles the Austrian-Hungarian border and covers 315 km.