Where's the entrance to the caves from Arkham West in Batman: Arkham Asylum?

You can access the caves through Secure Transit in Intensive Treatment Building. You can also go through Surface Access in Arkham North. One of the entrances in the Arkham North is behind the fence to the left of the Intensive Treatment Building and the other entrance is by the Entrance gates to Arkham Asylum to the left of the gates. It's in the northwestern section of the North Arkham Map.

There are 3 accesses. From Intensive Care from Elevator basement unlocked when Scarecrow escaped to Sewers via Croc's Lair. The ruins near Intensive Care gate opposite See Saw Riddle has one door leading to Sewers. You exit from here first time from Sewers. This is easiest to enter than Intensive Basement. Third is Deadman's point cave mouth behind wall next to Intensive Care near Arkham East gate. On return the animation of Batman jumping gliding down cliffs and opening Batcave entrance cut scene repeats everytime you come her after it first unlocks.