"Based on our port agreement with San Juan, unvaccinated guests will have to remain on board during our visits there," Carnival Cruises announced to guests.
"This is the most significant event in the past 50 years," said environmental health scientist Pablo Méndez Lázaro.
The Coal Seam Fire—so named because it sits along a coal seam—was set alight during the Plateau Fire, which hit the region in the summer of 2018.
As Puerto Rico has struggled to recover from the Hurricane Maria, Carmen Yulín Cruz and Trump have publicly feuded.
Trump also handed out flashlights, joking, "You don't need them anymore," though most of Puerto Rico remains without power.
For days, the president has accused San Juan's mayor of being politically motivated in her criticism of the federal government's response to the crisis.
Puerto Ricans need food, electricity and access to clean water. They also need a President who cares, say people across the island, who disagree with the President's assessment that the island is "doing well" on "food, water and medical" supplies.