Michael Bennett, 25, a popular YouTuber called Nuggetnoggin, took the phone back home to see if it could be salvaged.
He pulled off the waterproof case and it surprisingly worked. He called the phone's owner, who had lost it over a year ago.
Erica Bennett, 39 and not related to Michael, says she was shocked to hear the gadget still worked.
"I was totally shocked. I mean this is unbelievable, like 15 months underwater in the river for a cellphone to work,” she told Inside Edition. “It is a miracle"
She says the phone fell off her lap while she was tubing on the Edisto River in Charleston.
"To clarify I didn't get inside her phone,” Michael Bennett said. “I removed the sim card from the iPhone, I put it inside an older iPhone, pulled up contacts and it showed her contact number. I don't have any other information so it's still secure."
Getting her phone back meant the world to Erica Bennett, because it contained something irreplaceable.
"The most important thing about getting that phone back was the text messages from my late father,” she said.
The strangers now share a bond over a lost phone now found.
"I’m thankful that you got it back to me,” Erica told Michael.