Geneva police are calling for witnesses after an elderly man got into trouble while swimming in the lake near Collonge-Bellerive.
Several people dived into the water and helped him to the shore. But many had left by the time police arrived.
Police would like to talk to them.
The man is a bald 65-year-old English speaker – who speaks French – and lives nearby.
Anyone with information is asked to contact the Geneva Lake Police.