Sea World marine sciences director Trevor Long says a team has been keeping a close watch on the seal since it was spotted in Tallebudgera Creek on Saturday.
Efforts to capture it failed on Monday.
Mr Long says New Zealand fur seals are not usually seen so far north and it could be at risk from dogs and people if it tries to climb ashore.
It's hoped the seal, believed to be about two-years-old, will find its own way back to open water.
"The animal is OK, it appears to be quite healthy and in a reasonable condition," he says.
"But it's not good for them to live in fresh water and it's right up to the point where it is almost in fresh water."
Mr Long urged people not to seek out the animal.
"What we don't want is a whole lot of people going down there (to visit the seal)."
Mr Long says the sighting so far north is unusual.
"We get an occasional (seal) here in winter, but usually there is something very wrong with them."
The Department of Environment and Resource Management and Sea World is continuing to monitor the situation.
