We like to think we’ve already discovered everything there is to discover on Earth, but have we really? Throughout the course of history, a number of islands have been spotted and documented by early explorers, only to never be seen again. These territories are known as “phantom islands,” but as artist Andrew Pekler notes, their existence has never been verified.

In exploring the legends surrounding these elusive—and perhaps imaginary—islands, Pekler created an online “sonic atlas” of what these places may very well sound like. His work was commissioned by French museum Jeu de Paume for the exhibition “Fourth Worlds: Imaginary Ethnography in Music and Sound.”

“Poised somewhere between cartographical fact and maritime fiction, they haunted seafarers’ maps for hundreds of years, inspiring legends, fantasies, and counterfactual histories,” Pekler says of the phantom islands in an online description of the project.

Viewers can use their computer's mouse to navigate the map and zoom in on any islands that seem particularly intriguing. You can also enter “cruise mode” to be taken on an audio tour of all the phantom islands documented by Pekler. A brief history is given for each island, and some of them are pretty spooky.

One phantom island in the Gulf of Mexico, Bermeja, first appeared on maps in the 1530s but wasn’t seen again after the 16th century, according to research by Pekler and his team. The Mexican government sent a survey vessel to try to find it in 1997, but when nothing was uncovered, a few Mexican senators claimed America’s CIA may have destroyed it in a bid to lay claim to the territory and secure control over offshore oil and gas fields. Not long after, one of the senators who demanded further investigation was driving in his car when he was run off the road and killed by an unknown assailant, which spawned a number of conspiracy theories.

These stories are only made more chilling by the haunting chimes, bizarre bird calls, and underwater sounds that accompany them. To see it for yourself, check out Pekler’s website.