You can unlock Chef RPG mining by completing story quests until you've progressed to Act 2. One of the consequences of these quests is the removal of the barriers on the caves in the southwest portion ...
BEST OF 2019: The Veryovkina Cave is the deepest known cave on Earth. It took half a century and about 30 expeditions for Russian cave explorers to reach its record depth of 2,212 metres.