The two men set off for a spot of kayak fishing near the Browns Bay reef - however, the day turned sour when their boat capsized in rough and windy conditions.
One of the men couldn't swim, while the other man's lifejacket was ill-fitting and sitting up around his ears in the water.
They had no form of communication but got lucky when someone spotted them from the shore and alerted the Coastguard at 9.30am.
They pulled the hypothermic duo from the water covered in fishing hooks that they had been using to fish with.
A senior Coastguard crew member was "quite concerned" about their condition and they were taken to North Shore Hospital.
"We quickly wrapped them up in blankets and rushed them into Browns Bay so that the ambulance could take them to hospital to treat their hypothermia as well as ensure there was no water in their lungs which could cause secondary drowning," Coastguard North Shore volunteer Simon Allard said.
St John confirmed they transported two patients in moderate condition to North Shore Hospital's emergency department.