Slugterra is a massive underground world, divided into 99 caverns, each with their own slugs and history. In episode 1 of Slugterra it says there's only one way back to the surface. Some believe it's through the 99 caverns and the Slug's energy. Acording to Eli there are great evils hidden beneath Slugterra held in check by the energy of the Slugs.
Far and above, SlugTerra is largely populated with humans and Slugs. However, it is also home to a number of other species, both sapient and otherwise. While some species, such as Slug Hounds and Molenoids have a clear terran counterpart, other creatues such as the Behemoth seem to be fully unique to this underground world.
- SlugSlinger: Being a slinger is a full-time job! It's an action-packed career choice, full of travel and adventure. Almost all residents of SlugTerra have at least a small amount of slinging skill, but a handful have dedicated their lives to slinging.
- Security Slinger: Often deisparagingly refered to as "mall cops", the Security Slingers are a close-knit group who uphold justice in malls across SlugTerra. They're surprisingly skilled slingers, and take their jobs very seriously.
- Entertainment Slinger: The best of the slingers can make a career out of showing off their skills with a blaster. Mario Bravado is a beloved trick-shot slinger who stars in his own show.
- Blastersmith: Blastersmiths design, build, and repair blasters. As with any craftsperson, there are different levels of skill within this field. Red Hook is a master Blastersmith, considered by many to be the best in his field.
List of Caverns
- Tusker Forks Cavern (home of the Tazerling Slug)
- Low Rock Cavern (home of the Rammstone Slug)
- Scorched Sparks Cavern (home of the Lavalynx Slug)
- Quiet Lawn Cavern (home of the Grenuke Slug)
- Deaddrop Cavern (home of the Arachnet Slug)
- Chillbore Cavern (home of the Frostcrawler Slug)
- Deadweed Cavern (home of the Frightgeist Slug)
- Wild Spores Cavern (home of the Vinedrill Slug)
- Undertow Cavern (home of the AquaBeek Slug)
- Scrapheap Cavern (home of the Xmitter Slug)
- Lumino Cavern (home of the Phosphoro Slug)
- Cavern of Time (home of the Neotox Slug)
- Snowdance Cavern (home of the Slyren Slug)
- Bull's eye Cavern (home of the Fandango Slug)
- Magma Cavern (home of the Forgesmelter Slug)
See more at The 99 Caverns
- Stinkhole Swamp(home of the Flatulorhinkus Slug)
- Cinder Rapids(home of the ultra rare Infurnus Slug)
- Deadman's Reef
- The Deep Caverns (technically not a part of SlugTerra but still part of the underground)