French police are warning young people about the dangers of a dare spreading on Facebook that has left a young man dead and another severely injured.
Police confirmed that a 19-year-old had drowned after riding his bicycle into a port in western Brittany while a friend filmed him.
Another youth was injured for life after diving head-first into shallow water near Calais.
The challenge dares people to jump fully clothed into icy water while friends film it.
"Don't be influenced by a stupid phenomenon of the moment," national police warned on Facebook.