“System” Filling My Hard Drive

[Hrothgar]

I’ve seen a bunch of posts on the, but haven’t found solutions that help.
I’ve got a 2017 MacBook Pro running High Sierra. The 250 gb SSD has only 13gb free and I can’t upgrade the operating system because there’s no space.
Apparently the “system data” is taking up over 130gb of space. I can’t find any way to find out what this is or how to clean it.

I notice under Disk Utility there are two volumes. The Mac HD and “large files”. What’s that all about?

Any help would be greatly appreciated.

 

[Fishrrman]

Do you use time machine?
If so, could it be "snapshots" eating up your disk space?