Think of it like a tutorial for diving
Hogwarts Legacy has some really lengthy questlines, but The Lost Astrolabe isn’t one of them. You can pick it up near the start of the game, and it’ll teach you a few things about the basic swimming mechanic in the game. Here’s where to find it, and how to complete this fairly breezy quest.
Pick up the quest from Grace Pinch-Smedley, below Hogwarts
As one of the first sidequests you can acquire outside of Hogwarts, you’ll likely come across The Lost Astrolabe quest naturally. If you’re wondering where it is, the exact location of Grace Pinch-Smedley (the quest NPC) can be found in the gallery above.
Grace will ask you to find the Astrolabe, which was lost in the body of water in front of you.
Wade out into the water, and head for the purple circle on your minimap
All you need to do is dive into the water, and take a look at your minimap. See that big purple circle? That’s where you need to swim toward. Once you’re there, look for ripples in the water. There are several of them in the quest location, and they provide loot ranging from cosmetic items to the actual quest objective: the Pinch-Smedley Family Astrolabe.
Press the Square button (X on Xbox) to dive underneath each ripple until you find the Astrolabe. Swim back (or fly, as you can mount in the water) to Grace, and turn in the Astrolabe. Your choice here doesn’t really matter. You can chastise Grace, try and get more reward money out of her, or graciously give her back her family heirloom. Either way, you’ll get full quest credit.