About 7.6 million people, a 20 per cent increase on last year, are expected to pass through land, sea and air immigration border checkpoints during next week's "golden week" national holiday, government estimates show.
This year's National Day holiday period will be a day longer than usual as it coincides with the Mid-Autumn Festival, and the tourism sector expects a major influx of mainland visitors.
The industry predicts 924,000 mainland visitors will arrive, also 20 per cent up on last year.
But hotel managers fear disappointment for one of the most important weeks in the tourism calendar, with just 70 per cent of rooms booked. Prices are 15 per cent higher than last year.
The Immigration Department estimates are for the period from tomorrow to next Sunday.
About 5.88 million people are expected to cross the border in either direction by land, 77 per cent of the total, with Lo Wu border control point expected to be the busiest, with 296,000 people passing through every day.
The number of outbound passengers is expected to peak at 382,000 tomorrow, with Tuesday expected to be the busiest day for incoming traffic at 438,000.
Travel Industry Council executive director Joseph Tung Yao-chung expects the city to see an influx of mainland tourists who had planned to go to Japan until the dispute over the sovereignty of the Diaoyu Islands escalated in recent weeks.
He also expects a government decision to scrap charges for bringing small cars across the border to increase visits. Michael Li Hon-shing, of the Federation of Hong Kong Hotel Owners, said the cost of staying at a three-star hotel in a popular area would be between HK$1,100 and HK$1,300 per night, about 10 to 15 per cent more than last year.
Four-star hotels will charge HK$1,200 to HK$1,500.
But he added: "Some three-star hotels are less than 50 per cent booked. Some others, frequented by tour groups, have reached higher percentages."
Retail sales are likely to rise 13 per cent on last year, Caroline Mak Sui-king, of Hong Kong Retail Management Association said, with electronics and cosmetics likely to be the top-selling products with tourists.