Dandoran cave system.
Unknown to many tourists and wealthy party goers of Tipool City, but there is an elaborate cave system within the bedrock. This cave system can be accessed from certain points along the Nevo Race Track, specifically where the track meets the cliffs. There are also a few hidden entrances to the underground system from various places within the city itself. Some had entrances before the city was built, possibly made into storerooms for expensive wines and goods for the casino or palaces deepest points. Other entrances within the city were carved out to access the caves, possibly by smugglers.
The caves themselves are fairly dry and cool, while there are certain places within the system that contain small underground pools and rivers. Some phosphorescent flora and some fauna inhabit sections of the cave system. Some sections of cave are home to smugglers and pirates, while others are empty and lifeless. Who knows what dangers one can discover, for this vast system has not been fully explored yet.