"Everything seems to indicate that the fall happened when they were probably trying to take a selfie," Rui Pereira da Terra, head of the rescue service in Cascais port near Lisbon, told AFP.
"It seems they dropped their mobile phone and fell down while leaning over to retrieve it," he added.
The fatal accident happened in the coastal town of Ericeira, a popular surfing spot 30 kilometres (18 miles) from the Portuguese capital.
It was not the first time that tourists had fallen off the wall.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
Election Results for Lok Sabha Election 2019 will be out on May 23. Get the latest election news and live updates on ndtv.com/elections. Catch all the action on NDTV Live. Like us on Facebook or follow us on Twitter and Instagram for news updates from each of the 543 parliamentary seats for the election 2019