In Destiny 2, there are hidden enemy dungeons called Lost Sectors where you’ll find a boss and a chest full of valuable items. There are few dungeons on each of the four worlds: ETZ, Nessus, Titan, and Io.
In a Lost Sector, your goal is to get rid of the boss to get the key. So that you can open the chest and get the high-quality items and dealer tokens. However, the real task is to get into a lost sector first!
In the search for a Lost Sector, take a look at your map. On the map the Sectors are displayed with this symbol:
However, only the approximate location is displayed, the game does not automatically lead you into it. You must find the entrance yourself.
In the Open-World you should look for these symbols. They show you entrance to a lost sector.
All lost sectors in the European Dead Zone (EDZ)
All Lost Sectors on Titan, New Pacific Arcology
All Lost Sectors on Nessus, Arcadian Valley
All Lost Sectors on IO, Echo Mesa
Once you have looted a Lost Sector, it will be grayed out on the map. However, you can repeat it at any time. Just leave the sector and go back inside. Then again you have to defeat enemies to get to the chest.