Two men disappeared in Lake Constance after jumping into the water from a rental boat in front of their wives, police said on Friday.
The men, aged 71 and 76, remain missing despite a search operation lasting several hours.
The men were out on a hire boat with their wives on Thursday afternoon when they jumped into the water around 200 metres from Kirchberg harbour in south-western Germany and went under.
The water police and fire brigade were deployed on Lake Constance, which straddles Germany, Switzerland and Austria, while rescue divers, helicopters, tracking dogs and two sonar devices also took part in the search.
