The phrase "mysterious location" refers to a place that is not well-known or easily discoverable, and which has an air of mystery or intrigue surrounding it. Full definition
This time, the characters from the previous installments explore mysterious locations and underground facilities of the frosty Greenland. (gamepressure.com)
In order to save Cory, Sarah will travel through mysterious locations, solve plenty of puzzles, and learn the truth about the ghost of a beautiful young girl who roams Davy Jones» island. (blog.us.playstation.com)
And then there are the Cauldrons, mysterious locations said to be the birthplace of the machines, to search for. (twinfinite.net)