Encounter ideas for a cave system? (5.5e)

My party of level 5 players will soon be going into a large cave system that shifts and changes, making new rooms and tunnels every so often. To facilitate this, I want to use a d100 to roll for what room my players will find at any given time, meaning I need a lot of possible encounters.

The issue is, I'm not sure what to do.

Obviously, I can make a good number of combat encounters, but I also want exploration encounters, and even some role-play stuff in there. But I'm not sure what to do. I've always had a difficult time making exploration/skill check encounters, because I feel like they're too simple. With stuff like "get across the acid moat" or whatever, it's usually just a skill check or two, and that's it. I want these encounters to feel more impactful--maybe use up an actual resource or two and force my players to think outside the box.

If anyone could give me some advice on how to build better exploration encounters that might actually feel like good encounters and not just a roll of the dice, I'd really appreciate it! I'd also be very grateful for some ideas to jumpstart my creativity for what to put in this ever-changing cave.