Eco-tourism and adventure tourism are providing the Peruvian Pacific coast and islands with a substitute for the guano trade that was once the region's economic driver.

Located just 6 nautical miles southwest from the port of Callao and visible from Lima, the islands of Cavinzas and Palomino, which are part of the National Guano Islands, Islets and Capes Reserve, offer activities such as bird watching, fishing, and the chance to dive amid a colony of thousands of sea lions.

Every day, dozens of boats and catamarans approach the islands teeming with marine wildlife and home to derelict warehouses and piers that stand as relics of Peru's 19th-century guano boom.

Set off by the discovery that guano - accumulated excrement of seabirds and bats - made an excellent fertilizer, the boom lasted decades and even led to a brief conflict with former colonial power Spain, who sought to claim the islands.

"Tourism has even improved the islands," park ranger Elena Coronado told EFE. "Guano exploitation continued for a long time and it was important for the country's economy."

"The exploitation still goes on, but under a special plan," she said. "Tourism leaves room to preserve biodiversity and the guano birds, which, in turn, allows the collection of guano."

"Many people do not know what is on the guano islands, and we want to promote the sites," Isabel Iwaya, director of the Conociendo Peru travel agency, told EFE, pointing out that Cavinzas and Palomino are only 20 minutes from Lima.

Tourism complements the harvesting of guano, which is in demand among environmentally aware farmers and agri-business companies.