The Large Dune is a piece of interactive scenery that has spawned north of the Lumbridge Crater as part of the Dune Fractures event. It can be interacted with for either Runecrafting or Mining experience, as well as to check daily progress in the event.
Interacting with the dune takes 3.6 seconds for each action. This means that training for the maximum daily progress takes exactly 30 minutes without interruptions.
Experience
The amount of experience gained from a rift can be increased by using Dune menders.