The Nigerian Ports Authority said all vessels coming into Onne Port in Rivers state must observe the mandatory fourteen-day isolation on board before berthing.
This is in line with efforts to check further spread of the coronavirus through the land and sea borders.
In Port Harcourt, Governor Nyesom Wike is leading security agencies to enforce various restriction orders such as the closure of all markers in Rivers State.
He was also out to monitor compliance at places of worship to observe social distancing.
All land borders of the state have been shut while commercial flights at the Port Harcourt airport have been suspended. But operations are still ongoing at the Onne Port though with heightened consciousness caused the corona virus pandemic.
At the main entrance, visitors must wash and sanitize their hands and then get their temperatures checked before gaining access. At the main building, similar precautions are being taken.
The Nigerian Port Authority also said all arriving vessels must complete a minimum of 14 days at sea after take off from any high risk country before entering Nigeria through the Onne Port.
Port health officials then carry out mandatory medical screening of crewmembers to identify suspected cases of the coronavirus.
Where possible, the NPA said international crewmembers would not be allowed to disembark through out their stay.