A British man was missing on Monday after drinking and jumping off a bridge in Brisbane for "a bit of fun", Australian police said.
He was one of four men who decided to plunge off the William Jolly Bridge into the Brisbane River, roughly 10 metres (33 feet) below, after drinks at a backpacker's hostel on Sunday night.
"They had agreed between themselves that they were going to jump off the bridge for a bit of fun and to cool down," Inspector Sean Cryer told reporters in Brisbane.
"The young man in question, a 30-year-old British national, jumped off the bridge first."
Cryer said the man took a running jump from three or four metres away, leapt over a rail and went under the water.
"He came back up again a few seconds later, rolled on his side, went back under the water and hasn't been seen since," Cryer said.
He said the man's companions alerted emergency services after failing to find him and a helicopter with heat-seeking equipment was called in to scour the river without result.
"It's a very sad event obviously," said Cryer, who did not name the missing man but said his family had been contacted.
The search was continuing Monday.
"I think you would probably find that people have been jumping off that bridge since they built it. Sometimes they live and sometimes they die," Cryer added.