The Witcher 3: Wild Hunt is no doubt vast in scope, allowing you to explore a whole heap of areas, but if you've been wanting more, and have been eyeing up The Devil's Pit caverns, then you're in luck, as modder SkacikPL has provided a bot which allows you to access them, a trailer for which can be found here.
In the mod there's not only "old friends with new problems" but also some brand new additions, including a new steel sword, throwing knives, and a wearable hood. Repeatable doppler fights are also featured in the mod, and "immersive and intelligent follower NPC" that's capable of carrying your stuff, sparring, changing outfits, and (most importantly) playing Gwent.
SkacikPL is also behind the first-person mod for the game, so they clearly know their way around The Witcher 3, and for more on The Devil's Pit check out the official mod page. Could The Devil's Pit become your new favourite location?