When Royal Caribbean’s Oasis of the Seas pulled into Falmouth, Jamaica, this spring, passengers peering over guardrails saw a port bursting with local crafts, rum cocktails, reggae musicians and circus-style stiltwalkers. Everything was irie, as the Jamaicans say, and more.

Hours later, however, the cruise terminal appeared vacuumed-clean. The ship had departed, draining the color, the noise and the energy from the pier. Even the irie had vanished.

Pop goes the port.

This ephemeral terminal — a Port-in-the-Box hand-cranked by the cruise lines — differs from the permanent members of the sea tourist trade, such as Nassau, St. Thomas and even Montego Bay, Falmouth’s westerly neighbor. Because these destinations draw visitors all the time, a mixed salad of resort guests and cruisers, the vacation apparatus never shuts down. By comparison, Falmouth and its ilk revolve around the cruise calendar, folding down or springing up depending on the day of the week.

“We don’t have tourists every day,” said Delroy C.M. Ormsby, a local resident who manages a rental property a few miles from town. Vendors “don’t come here when there’s no cruise ship.”

I first experienced the pop-up phenomenon on a Caribbean cruise aboard Norwegian Cruise Line’s Epic.

Because of squirrely weather, the captain had to shuffle our itinerary, reassigning ports to different days of the week. but neglecting to tell the locals on the ground.

When we arrived in Mexico’s Costa Maya on a Tuesday instead of a Thursday, we found only a small gathering of retailers, not the usual swarm shouting out their services and specials. A few hustled to open their shops and stands, but most of the traveling merchants were probably north in Cozumel, greeting ships that had stuck to their schedules.

In late May, when Oasis of the Seas left Falmouth for Cozumel, I didn’t reboard. After disembarking with the other passengers, I turned my lens inland, focusing on the landscape that shifted with every sway of the ship.

When Falmouth learned in early 2000 that Royal Caribbean and the Port Authority of Jamaica were building a $180 million terminal on its waterfront, the residents rejoiced. Wedged between Montego Bay and Ocho Rios, the city suffered from an inferiority complex. Despite its sugar and rum history and its Georgian architecture (supposedly the largest intact collection in the Caribbean), the capital of Trelawny parish didn’t draw the same crowds as the popular resort towns. Moreover, when the country extended its North Coast Highway in 2003, it bypassed the city. Falmouth was reduced to drive-by status.

The once-prosperous trading port needed an economic uplift and a morale boost. The new pier and its job opportunities, plus an estimated 800,000 passengers by 2014, could provide both.

“When the cruise ships come in, Falmouth becomes another Ocho Rios or Montego Bay,” said Ricky Matthews, a Jamaican cruise director with Royal Caribbean. “It’s being discovered by people every week.”

Built on land reclaimed from the sea, the port features two berths that can accommodate some of the largest ships at sea. The number of passengers (6,300) and crew (2,000) aboard the Oasis of the Seas roughly equals the town’s population (8,912).