Director Colin Trevorrow has people out scouting locations for Jurassic Park 4, and he revealed that the story will be taking place back on the original Island from the first film, Isla Nublar. He ended up tweeting out the photo above. The two other sequels, The Lost World and Jurassic Park 3 took place on a different island, called Isla Sorna, a.k.a. Site B.
There's still no information on the plot of the story, but I like the fact that they will be returning to the original theme park island. I'm excited to see what it looks like 20 years later, and overrun with Dinosaurs. It will be interesting to see why the story takes place on the island. At this point, all we can do is speculate about what is going to happen.
Here's a map and some information on the island.
Isla Nublar is a remote island about 120 miles (190 km) off the west coast of Costa Rica, which is only 87 miles away from Isla Sorna. The island was intended to to be the site of Jurassic Park. It was to be a tourist attraction featuring living biological dinosaurs cloned from pre-historic DNA. The park was controlled from the Visitor Center. The sequence of disasters that led to the closing of Jurassic Park is nicknamed the Isla Nublar Incident.