It happened around 10:00 Saturday morning in the Christiana River near I-95.
Initial reports indicate that the man, in his 50s, was in his row boat when it flipped over and floated away.
The victim was in the river for about 45 minutes until he was spotted by a Department of Natural Resources police boat.
They were able to get him to land where medics treated him for hypothermia. The victim refused hospital treatment.