I’m not a caver or a diver, but I’ve read a few stories about cave diving. A big one is a cable on a retracting reel. Caves which are frequently explored will have guide cables bolted along the walls for long stretches. You snap your cable onto these and then use it as a leash back to the guide. This allows you to explore off a certain distance without getting lost. You can always follow your own line back to the guide, and follow the guide back out. In an “unimproved” cave, you’d presumably want lots of extra line to build your own guides.