I'm in Freya's Garden on the "Nameless" quest. I tracked Craven until I stood in fron of a locked door at the point marked on this screenshot:

I can't open the door, and haven't found a way around it so far. The quest description is not really helpful, it just states "Explore the further parts of the herbarium".
How do I get through that closed door?
5 Answers
Look for the stone ladder:


It is where Geralt looks at. It will not be shown from the Witcher's senses.
If you go all the way to the right of the garden you will find a ladder. Head up those and you should get a cutscene about the floodgates. I don't really know what they do yet (still doing the mission) but if you keep going you should come across the werewolf's cave where you can fight and talk to him.
2After reaching the locked door, go up and over to the right, going as far right and anti-clockwise as you can around the garden. This will end up rejoining you with the werewolf's tracks, and you can follow them over the little bridge that goes over the flood gates/canal. Over that bridge there is a ladder going up, it doesn't shine with witchers senses and is made of stone so it's a bit difficult to see. But once you climb that wall you can open the flood gates to proceed.
You will get a key during “In Wolf’s Clothing” (Secondary Quest) to open doors in Freya’s Garden.
1Advance "Nameless" until you track Craven to a well. When you jump down the well, you will find Craven's body and trigger a cutscene with Yennefer. Once the cutscene is over, you will find yourself back in the garden.
To get the key that opens the wooden door with claw marks at the Entrance marker, you will need to return to the well and jump down again. This time, you can walk past Craven's body to the exit. Before exiting, loot the skeleton and receive the key to Freya's Garden. You will be able to unlock the door from the inside, and exit the cave.