PORTLAND, Maine — Tens of thousands of dollars poured into the city of Portland this weekend, with two large cruise ships docked at the Portland Ocean Terminal on Saturday.

“It’s real nice to have a double cruise ship day,” Bob Leeman, cruise ship marketing manager for Portland, said.

Leeman said September is the busiest month of the year for cruise ships in the city.

“The cruise ships are coming in absolutely full. We have about a 15 percent increase from last year on passengers,” Leeman said.

Explorer of the Seas is the largest ship to dock in Portland this year, bringing in more than 3,000 passengers Saturday.

“We’re very pleased, and we have a trend that’s continuing in that direction,” Leeman said.

A 2009 study found the average passenger spent $120 per day in Portland. With nearly 6,000 people in the city this weekend alone, business owners say it’s a huge boost for the area.

“I’ve been doing this for two years, and every year it’s been getting better and better,” Khaled Habash with Scenic Route Maine Tours said. “I keep adding more vehicles to keep up with the demand.”

Leeman said the plan is to keep visitors coming. He said they have Norwegian Cruise lines booked through the next four years.

“We’re going from two ships this year to five next year, seven the following and then eight in 2018,” Leeman said.

Passengers said they shouldn’t have trouble filling capacity.

“Everything is in walking distance — this is what’s nice. You don’t have to get on a bus and take a 50 minute hike just to see the place. It’s so nice,” said Leslie Plummer, a visitor from England.

“One of the hidden secrets I think, one of the unadvertised places to stop,” Larry Hall from Springfield, Missouri said.