Unlike the drifting sargassum that affects Mexico’s Caribbean coast, researchers said the algae found around Puerto Vallarta grows locally—and warned that water pollution could cause it to proliferate.
Editor’s note, July 2026: This article was originally published approximately 10 years ago. It has been lightly edited and republished as VallartaDaily reports on unusual sargassum accumulations along parts of the neighboring Nayarit coast. The research, quotations and environmental conditions described below reflect the situation at the time of the original report.
University researchers addressed the presence of sargassum in Puerto Vallarta, Jalisco. Although the small patches of seaweed visible in photographs and videos from Mismaloya Beach were minimal, the academics feared that water contamination could aggravate the situation.
In Mexico, the macroalgae had already invaded the coasts of Cancún, Tulum, Playa del Carmen and Puerto Morelos, where it caused an unpleasant smell and appearance that discouraged visitors.
In the case of Jalisco, scientists explained that sargassum found on the beaches of Puerto Vallarta does not travel across the sea like the sargassum reaching Cancún. Instead, it grows on the seabed or rocks. During the hot season, it can break away and reach the coast.
Amílcar Leví Cupul Magaña, a research professor at the University of Guadalajara’s coastal campus, said the presence of the algae in the area was common. However, researchers feared that excessive pollution could aggravate the situation.
“It is seen mainly on rocky beaches, and this is the season in which it becomes evident. This sargassum grows in Puerto Vallarta, unlike the sargassum in Cancún, and with the swells it breaks away and can reach heights of one meter,” he explained.
Researchers said sewage discharges could alter the algae’s natural cycle and cause it to proliferate in large quantities. In March of that year, two Puerto Vallarta beaches were closed following an intentional sewage discharge after the collapse of a collector.
“Sewage is loaded with nutrients, and that is like giving the water fertilizer. It can also lead to harmful algal blooms or red tide,” Cupul Magaña added.
Before the situation worsened, the academic said it was urgent to implement measures to prevent the problem from affecting the ecosystem and tourism, as had already happened in Quintana Roo.
Puerto Vallarta was already one of Mexico’s most visited destinations, particularly among adult and retired travelers from the United States and Canada.
