Aphelion's Rest, Chamber of Starlight and Bay of Drowned Wishes are The Dreaming City Lost Sectors you'll encounter in Destiny 2.
Though you can visit them at any time once you unlock The Dreaming City as a Patrol area, they will be required to unlock certain questlines and bounties for Petra, so learning their locations will come in handy.
If you are new to The Dreaming City, be warned these are a high level - 560 - so don't be surprised if you need to come back much later!
Looking for more Lost Sector locations in Forsaken? Learn where to find all of the Tangled Shore locations as part of the Broken Awoken Talisman quest.
On this page:
Aphelion's Rest location
Aphelion's Rest is in The Strand, next to where you find Petra:
Specifically, jump down to the east from the elevated area where Petra is, to the waterlogged area below. Look toward the wall now, and you'll see the Lost Sector symbol. The cave is right next to it.
Take the linear path through the cave to arrive at the Aphelion's Rest location.
Chamber of Starlight location
The Chamber of Starlight location is in Rheasilvia, the area to the north of The Dreaming City. Specifically, it's just south of the Public Event that regularly spawns there:
You want to locate the bridge where the Public Events start. This is what you'll see when approaching from the south, with a fountain to the north-west:
Now look south from the bridge, and in the valley below, you'll see the Lost Sector symbol at the very end:
Jump down to the right side of the valley and make your way to the very end.
Make your way through and you'll eventually reach the Chamber of Starlight location.
Bay of Drowned Wishes locations location
The Bay of Drowned Wishes location is the easiest of the three locations. First, travel travel to the Divalian Mists fast travel location:
Next, turn around and you'll see the Lost Sector symbol just peeking out over the top beyond the rock. Leap on the rock to see it clearly.
There is a cave next to the symbol - follow it round.
Soon, you'll come to the Bay of Drowned Wishes Lost Sector location.