After two seasons of mystery, the Westworld season 3 premiere finally confirms the location of the park: an island in the South China Sea, near the Philippines. In "Parce Domine," Bernard is trying to lay low after being liberated from Westworld by Dolores. During the aftermath of season 2, Delos needed a scapegoat for the hosts' disastrous rampage through the park, and decided to pin all of the blame on Bernard, characterizing him as a rogue programmer who introduced code to make the robots go crazy.
When he is identified by two of his fellow workers who plan to turn him in for a bounty, Bernard goes into an automated combat mode that allows him to violently overpower them. Forced to flee, he ends up heading to a fishing port. There, a sign behind him reveals that he is on Palawan, an island in the Philippines. Bernard approaches a fisherman, shows him a large wad of cash, and tells him that he's "looking for a friend." The man asks him where he's going, and Bernard pulls out a map that finally reveals the location of Westworld.
Off the west coast of Palawan, the area that Bernard gestures to on the map, is an archipelago called the Spratly Islands - though even the largest of these islands is far too small to contain Westworld, let alone the other parks as well. Delos Destinations' island appears to be man-made and built for purpose, though it could have been terraformed out of the shallow waters of the archipelago. Its location is no secret to the people of Palawan; when Bernard says that he wants to go to Westworld the fisherman looks surprised, but agrees to take him there.
The ambiguity of Westworld's location has, in the past, been used to emphasize the impossibility of escape, with Delos granting the only transport on and off the island. Some fans even theorized that the island could be on an alien planet. It was previously implied by the presence of the Chinese Navy that Westworld was somewhere near China, but we now have a confirmed location.
The some other returning character from season 2? Whoever it is, they must be very important for Bernard to risk everything by going back to his old prison.