World's 'Most Dangerous' Place: Inside Island Overrun by Venomous Snakes That Kill With a Single Bite

" Snake Island," or Ilha da Queimada Grande, is an aptly named island in Brazil with the highest density of venomous snakes anywhere in the world.

Knew.com has learned that the isolated land is home to thousands of golden lancehead vipers , a unique pit viper species.

The golden lancehead is endemic to Snake Island, with a density ranging between one to five snakes per square meter (around 10.76 square feet).

This specific pit viper species, which grows over two feet long, is considered one of the most venomous in the world and has a bite that can kill a person in under an hour, an evolutionary trait it developed after being left stranded on the isolated island.

The Smithsonian Magazine wrote that Snake Island was cut off from the Brazilian mainland around 11,000 years ago, following the end of the ice age , causing the native snake species "to evolve on a different path than their mainland brethren."

"The snakes that ended up stranded on Ilha da Queimada Grande had no ground level predators, allowing them to reproduce rapidly. Their only challenge: they also had no ground level prey. To find food, the snakes slithered upward, preying on migratory birds that visit the island seasonally​ during long flights," the Smithsonian Magazine explained.

"Often, snakes stalk their prey, bite, and wait for the venom to do its work before tracking the prey down again. But the golden lancehead vipers can't track the birds they bite—so instead they evolved incredibly potent and efficient venom, three to five times stronger than any mainland snake's."

Bites from the golden lancehead viper have a 7% chance of death, and 3% of victims could die even after the bite is treated. According to BBC Science Focus , symptoms of a golden lancehead bite include kidney failure, internal bleeding, and tissue death.

Given the potent nature of its venom, visits to the uninhabited Snake Island are strictly restricted by the government of Brazil.

"The Brazilian government requires that a doctor be present on any legally sanctioned visits, in the event of an unfortunate run-in with the island's native population," the Smithsonian Magazine mentioned.

"The Brazilian navy does make an annual stop on the island for maintenance of the lighthouse, which, since the 1920s, has been automated."

Lighthouse keepers were the only inhabitants of the island during the brief stretch from 1909 to the 1920s. Legend has it that the last lighthouse keeper, along with his entire family, was killed by several snakes that broke into their home through the window.

Biologists and researchers are granted special permission to visit the island to study the critically endangered snake species.

One of the reasons the golden lancehead is studied is because of its venom, which has shown promise in the field of pharmaceuticals .

Marcelo Duarte from the Butantan Institute in São Paulo, Brazil, said in an interview with Vice that the venom has shown potential in the treatment of heart disease , circulation, and blood clots. "We are just scratching this universe of possibilities of venoms," Duarte said.

Despite steps taken by the government, golden lancehead numbers keep decreasing, falling prey to habitat loss, disease , illegal poaching, and the negative effects of inbreeding in this isolated population, per BBC Science Focus .

Notably, the golden lancehead population has decreased by nearly 50% in the last 15 years, placing the species on the International Union for Conservation of Nature 's Red List.

The Smithsonian Magazine noted that golden lanceheads can go for anywhere from $10,000 to $30,000 per specimen on the black market, encouraging poachers to try and trap this deadly reptile.

These majestic snakes can be viewed in captivity at the São Paulo Zoo enclosure that contains five adult golden lanceheads.