An iPhone lost at the bottom of a river still works 15 months later.

The handset fell overboard when Erica Bennett and her family went on a tour with Edisto River Adventures in South Carolina, and thanks to a waterproof case it still functions.

YouTuber Michael 'Nugget Noggin' Bennett - no relation - was diving in the body of water earlier this month when he found the device over a year after Erica thought it was gone forever.

"I came across something that looked kind of like a rope maybe attached to car keys,” he said.

“When I pulled it up, I saw a phone inside of a waterproof case, and I'm like no way this is unbelievable."

He was able to charge the phone and contact Erica to return it to its owner.

She said she was massively relieved, with the phone containing sentimental messages from her late father.