A Mormon missionary who died at a popular whale-watching site in Sydney's south has been described as a "bright light" who loved spending time in Australia.

Gavin Paul Zimmerman, 19, from the US state of Utah, slipped while taking photos at Cape Solander in Kurnell yesterday afternoon.

The local Mayor said police had recovered a mobile phone with photographs of the teenager taken moments before he fell.

Speaking from the US, his friend Gio Grillo said he had promised to take photos of the area for her.

"He emailed me right before he left with the other missionaries," she said.

"We talked about things we were going to do after he got home from his mission and how excited he was to reach his one-year mark [in Australia] in August," she said.

"Then he said he might lose signal because they were going to the cliffs and so he said he would take lots of pictures and email me next week to show me."

The tourist fell up to 30m from the clifftop. ( Trip Advisor: Agro_Sydney )

Mr Zimmerman's parents, Raymond and Jeanette Zimmerman, released a statement through The Church of Jesus Christ of Latter-day Saints.

"It is with deep sorrow and heavy hearts that we share the news of our son's passing from this Earth to return home to his Heavenly Father," it said.

"Gavin was a bright light in our lives! He was a great example to us all, and he loved his mission very much."

A spokesman for the church said its sincere condolences and prayers were with Mr Zimmerman's family and loved ones.

Gavin Paul Zimmerman, 19, was working in Sydney as a Mormon missionary. ( Supplied )

Ms Grillo said her friend was due to finish his mission next August and had been making the most of his time in Sydney.

"He would always write group emails to everyone back home and they would always say how pretty Australia was and how much he enjoyed being a missionary there," she said.

"He touched so many peoples' lives while he was in Australia for such a short time."

Mr Zimmerman died in the same spot where another man fell to his death last month.

Police have urged people to stick to the whale-watching platform and not to climb onto the rocks below.