The orders took effect on Friday after the government reported the highest number of 6,830 coronavirus cases in the daily count.
Md Mominur Rahman, deputy commissioner of Chattogram district, said eateries will also remain closed after 6pm but pharmacies and kitchen markets may stay open.
The authorities may announce more stringent measures on Saturday, he added.
More than 200,000 travellers visit the seven tourist spots in the Sundarbans every year, but the number fell to around 170,000 last year due to the pandemic closure, according to Belayet Hossain, divisional forest officer of the Sundarbans East.
Azad Kabir, in-charge of Karamjol Wildlife and Tourism Centre, said the number of tourists had been dropping since the coronavirus cases began to rise again.
Earlier, the government closed the tourist spots in Chattogram, Cox’s Bazar, the three Chittagong Hill Tracts districts, and many other places, including zoos.