Waiheke and Aotea Great Barrier islands will be out of bounds for Aucklanders wanting to get out of the city under eased lockdown restrictions.
The government has granted a health order meaning only residents or those with essential reasons will be able to travel there.
Local residents had expressed concern that large numbers of visitors would head to the Hauraki Gulf islands for day trips, where there are limited medical resources should a Covid case crop up.
Waiheke local board chair Cath Handley said she is incredibly grateful for the restrictions, as she feared thousands of Aucklanders heading to the island could present major Covid risks.
"The notion of rubbing shoulders with people who have come from Auckland - as much as we love them - was a cause of great concern," she said.
Handley is also concerned around Waiheke's vaccination level, as she said that information had not yet been made available by the District Health Board or Ministry for Health.
"So we're not sure to what extent our population is already resilient in the sense of being vaccinated."
Handley had requested that Waiheke be moved down alert levels if the border was put in place. She said that would not be happening at this stage and island residents would still be able to travel to Auckland.
"People who have families and are looking to do their bubble outings... they can still do that but it will just have to be on the mainland and not on the island.
"But those going from Waiheke, we would just ask them to really exercise caution."
Police will be at the Auckland Ferry Terminals monitoring the border, with the Maritime Unit also out on the water.
The same rules apply for Aotea Great Barrier. Local board chair Izzy Fordham said it was a relief to have them in place.
"This gives us some clarity and certainty going forward when we come across people that shouldn't be here."
Some of those unwanted visitors have already begun arriving - a group of eight to 10 boats turned up off Raketu Island, just off Aotea, first thing this morning.
"We're just looking into various options for assistance with that and to ask these people to please return - after all, Raketu is part of Aotea Great Barrier, so that's a bit of a bummer to be perfectly honest.
"I appreciate the fact that people would be longing to sort of break the mundane life that we've all been experiencing these past seven weeks and would be loading up the boats and whatever, just please don't come here at the moment."
On Monday Auckland Mayor Phil Goff said different alert levels within the city were not practicable, but today said the island restrictions were sensible, given the limited healthcare services that were available.
He said similar borders in other remote parts of Tāmaki Makaurau would need to be guided by health advice.