Aberdyfi Search and Rescue volunteers were called in after emergency calls from the pair, a man and woman from Northampton,.
They raised the alarm at around 5.30pm on Tuesday, saying there were lost in mist.
Graham O'Hanlon from the search and rescue team said: "They been following a way-marked trail but lost the markers and ended up in an area of deep heather and gorse.
"Disorientated and confused in deteriorating conditions, the couple were not able to offer any idea about their whereabouts other than being above the lake and that they parked at the dam end."
"With phone signals too poor to make use of any of the usual strategies to quiz smart-phones for location information, it took some inspired detective work on the part of the call handler to be able to transform this information into a feasible search area."
Mr O'Hanlon said team volunteers made their way to the Lake Vyrnwy Hotel car park where the local gamekeeper was able to escort a vehicle up a hill track to within a few hundred metres of where the pair were eventually found, cold but uninjured.