Cut an opening or hollow into a solid terrain platform. The cave shape represents the volume to remove, so part of it must intersect the platform to produce an opening.
You need an editable terrain with Include bottom and sides enabled. Open terrain has no solid body for this operation. An imported cutting shape must be a closed static mesh with no more than 30,000 triangles.
Create The Cutting Shape
Refine The Opening
Choose Sculpt negative to shape the cave. Draw, Smooth, Grab and Flatten adjust the form; Add and Excavate provide further sculpting choices. Use smaller strokes near the entrance and inspect the terrain result regularly.
Subtract from landscape controls whether the cut is active. Hiding the helper alone does not turn off subtraction. Join smoothing controls the transition where supported; a zero radius disables that blend.
Keep A Failed Stroke Recoverable
After finishing a sculpt stroke, let its save complete. If Stage offers Retry retained edit, retry the retained work rather than sculpting the same stroke again. Discard it only when you intend to lose that unaccepted change.
A missing source can offer Retry cave source. Treat an unavailable or failed cave result as unresolved; check the final cut and the document save state before continuing to presentation or rendering.
Return to landscape for terrain, planting and flow choices around the opening.