(UPI) A family of hikers who became stranded above a 40-foot waterfall in California were rescued thanks to a message in a bottle and pair of strangers who found the request for help.

Custis Whitson, 44, said he was backpacking the Arroyo Seco River with his girlfriend and his 13-year-old son and after about two and a half days of trekking, they ended up at the Arroyo Seco narrows, a spot on the river surrounded by 40-foot walls of solid rock.

Whitson said the river current was too strong for them to pass, and he discovered a rope that he expected to be in place for them to rappel down was missing.

The hikers searched the area and discovered they were trapped, but they could hear voices somewhat nearby. Their calls for help went unanswered, so they carved "Help" on a Nalgene water bottle and inserted a note reading: We are stuck at the waterfall -- get help please.

The family tossed the bottle over the waterfall and set up some rocks on a tarp reading "S.O.S." to help rescue crews find them.

Hours later, they were found by a California Highway Patrol helicopter. The CHP said two hikers found the message in a bottle and contacted authorities to begin a search.

The hikers who found the bottle didn't give authorities their names, but Whitson said he is hoping to identify them so he can thank them personally.

Copyright 2019 by United Press International