Son Tra Peninsula, which covers more than 4,400 hectares (10,880 acres) and rises to 700 meters at its peak, acts as a natural shield for the central city of Da Nang.

The peninsula was originally an island before ocean currents and sediment linked it with the mainland.

It is now around 10 kilometers to the northeast of Da Nang and bordered by the sea in three directions.

Vu Ngoc Long, former director of the Southern Institute of Ecology who spent many years studying Son Tra, referred to it as a “treasure” with a closed ecosystem varying from tropical rainforests to coastal reefs.

“Without protection, its ecology, coral reefs and seafood resources will all be hit, as well as the sand quality on Da Nang beaches,” Long said.

Various studies show that the peninsula can generate enough oxygen for more than four million people.

Home to hundreds of species of fauna, including 22 endangered species, the peninsula is best known for the world’s largest population of the endangered red-shanked douc langur.

Red-shanked doucs (Pygathrix nemaeus), also known as "costumed apes” due to their striking appearance, were first detected on Son Tra in 1969. They mostly live in groups of five to ten at altitudes of 100-600 meters, but some live right by the sea.

The monkeys, which have been selected as Da Nang's symbol of biodiversity, are at high risk from poaching.

A court in Da Nang earlier this month sentenced a man to three years in jail for setting up snares to catch the primates on the peninsula two years ago.

But their biggest threat is deforestation, which is usually carried out to serve tourism. Studies by the GreenViet Biodiversity Conservation Center in Da Nang found the primate reserve on Son Tra has shrunk to less than 2,600 hectares over the past decade from its original 4,400 hectares.

Their habitat could shrink even further with a national tourism plan approved by the prime minister last November set to leave them only 1,826 hectares, and reduce the forest coverage by half on the peninsula.

The plan has been put on hold after receiving strong public criticism, including an online petition set up by Da Nang's Tourism Association asking for the peninsula be left alone.

“There should be no further construction,” said the petition, which has received over 11,000 signatures. It said Da Nang already has enough hotel rooms to welcome 15 million tourists a year, and only received 5.5 million last year.

Architect Hoang Su, former director of Da Nang's Urban Planning Institute, said that even before the tourism plan was announced, Da Nang had already licensed 14 villa and resort projects that would cover over a third of the peninsula. A high-end resort that opened in June 2012 was named the world’s leading luxury resort in 2015 by the World Travel Awards.

The entire peninsula is fragmented by roads and is regularly burdened by noisy traffic.

Su said the burst of the real estate bubble around a decade ago had held up a number of projects, which could be a chance for preservation efforts to prevail.

Nguyen Dong