Businesses across north Wales say they fear local lockdowns could lead to job losses or even closures.
New restrictions will come into force across Conwy, Denbighshire, Flintshire and Wrexham at 18:00 BST.
It means those living in the areas will not be able to leave or enter without a “reasonable excuse” such as work or education.
However, businesses reliant on tourists said they were facing confusion over the rules and financial uncertainty.
The restrictions – the same as those seen in most of south Wales – will see another 500,000 people living under tougher restrictions than at the start of September.
Conwy council leader Sam Rowlands said he was “disappointed and frustrated” the Welsh Government did not take measures to protect tourism which would lose out again.
Among those braced for another hit is the SeaQuarium in Rhyl which relies on day trippers and visitors from outside Denbighshire for as much as 90% of its business.
“It’s a real struggle,” said director Colette Macdonald.
“We were hoping we had a lifeline when we were able to reopen but we’re 40% down on last year and my fear is that we will lose the October school half-term as well.
“It’s also very difficult for attractions with animals. We can’t just pull down the shutters and come back six months later.
“We have constant bills such as vets, heating and food for the animals. Our electricity bill alone is £5,500 every month – and we are almost entirely reliant upon visitors for revenue.
“We’ll have to reduce staff hours and possibly make redundancies if the lockdown continues. It’s tough and very deflating.
“Zoos and aquariums in England get special help but in Wales we are regarded as part of the hospitality sector. We need more help from the Welsh Government.”
The Welsh Government said: “Earlier this year we wrote to zoos in Wales with details of existing schemes which they may be eligible for funding, as well as issuing a questionnaire to identify key animal welfare concerns and whether any funding gaps exist.”
Businesses have also complained the difference between rules in Wales and England over travel for holidays has caused “mass confusion”.
First Minister Mark Drakeford has called for Boris Johnson to ban people in locked-down parts of England from travelling to Wales on holiday.
The owners of Halkyn Castle Wood campsite, near Holywell in Flintshire, rely on visitors from across the border.
“The differences in the rules are very confusing,” said Venessa Warrington, 44.
“People are ringing and at times we don’t know what to tell them. We’re just going along with the advice given by Visit Wales.”
The family-run campsite, like so many businesses in the tourism sector, is facing an uncertain future.
“My heart sank when we heard the latest lockdown announcement,” said Mrs Warrington.
“It has been a very difficult year. I worked out to the penny how long we could go before we would have to sell the family business.
“We’ve extended the season longer than usual to make up for lost months but our financial problems will only get worse if we’re forced to close again.”
The National Trust said lockdown offered local residents a chance to enjoy its sites across the region, such as Bodnant Gardens, Erddig and Chirk Castle, without bustling crowds. However visitors must still book in advance.
“Over the past few months it’s become clear just how much we all need fresh air and open space, so we’re keeping our places open for local residents to get closer to nature and watch the season unfold,” a spokeswoman said.
What are the rules?
Under the restrictions no-one can leave or enter a lockdown area except for a limited set of reasons, including:
- to work, if you cannot work from home
- to provide care
- travelling to education
- elite athletic training and competitions
- to provide or receive emergency assistance
- to meet a legal obligation, and to access or receive public services
- to avoid injury or illness or escape a risk of harm
It is permitted to travel through the areas concerned, so motorists can continue to use the A55 to get to or out of Gwynedd and Anglesey.
Rules allowing people to meet extended households are suspended, meaning people can only be with their usual household when indoors, including in pubs and restaurants.
Other Wales-wide restrictions apply, including the wearing of face masks in shops.
Covid-19 case rate changes in north Wales
Cases per 100,000 people, seven day rolling average
Conwy has seen 46.1 cases per 100,000 people in the latest week, while the equivalent figure for Denbighshire was 37.6.
In Flintshire it has risen to 53.8, and Wrexham it is 43.4.