Rina's maximum sustained winds have increased to 105 mph (165 kph), said the U.S. National Hurricane Center in Miami, making it a Category 2 storm. Forecasters predict it will strengthen as it nears the Mexican coast Wednesday night before rolling over the island of Cozumel, a popular dive spot and cruise-ship port, then along the coast to Cancun.
The area, dotted with Mayan ruins, also includes Playa del Carmen, another popular spot for international tourists.
Cancun Tourism Director Maximo Garcia said the city alone now has about 22,000 tourists even in the pre-holiday low season. Quintana Roo state as a whole has some 83,000 hotel rooms, most in the Mayan Riviera-Cancun area.
Laura Valles, a receptionist at the Hotel Jashita in coastal Tulum, said four of its 15 guests chose to move inland to hotels at the archaeological site of Chichen Itza, some 90 miles (150 kilometers) west, and others were still deciding what to do.
"We are letting those with a reservation know they will have to change their dates," Valles said.
Yassir Espinoza, a clerk at the small Plaza Azul hotel in Cozumel, said tourists were being warned of the impending storm.
"We told them if there is a hurricane there won't be any electricity or water for at least three days," she said.
In Cancun's hotel zone, a string of pick up trucks hauled small boats and jet skis away from marinas, while workers at shopping malls began boarding up windows.
At least eight cruise ships were changing itineraries away from the storm's path, said Carnival Cruise Lines spokesman Vance Gulliksen.
Three cruise ships from Norwegian and one from Royal Caribbean have canceled their Friday port of call in the area, said Hiram Toledo, port administrator for Quintana Roo state, where Cancun is located.
The area was badly damaged by Hurricane Wilma in 2005, when Cancun's famous white-sand beaches were largely washed away. Insurance officials estimated total damage at $3 billion.
State officials said they were readying more than 1,100 shelters that could handle nearly 200,000 people, though so far there was no word of any planned evacuations.
The hurricane was centered about 290 miles (465 kilometers) southeast of Tulum Tuesday afternoon and it was moving west-northwest at near 3 mph (6 kph), the Hurricane Center said.
Forecasters said it was likely to strengthen into a Category 3 hurricane with sustained winds of about 115 mph (185 kph) by night.
The forecast track shows it curving east toward Cuba by the weekend, but senior hurricane specialist Michael Brennan at the Hurricane Center said it could also move toward southern Florida.
The Center said the storm could produce as much as 16 inches (40 centimeters) of rain over at least parts of the eastern Yucatan Peninsula while raising water levels by as much as 5 to 7 feet (about a meter) in places.
The rainfall particularly worries authorities in the Gulf coast state of Tabasco, where about 300,000 people are still flooded following eight days of heavy rains.
In Central America, affected by Rina's outer bands earlier, fishermen on Monday found a Nicaraguan Navy boat that had gone missing with 29 people aboard. It had been used to evacuate an island.