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.

As a starting point you could use one of the underdark encounter tables from the Monster Manual (2024), and replace the more aberrant underdark monsters with non-combat encounters. For more resource expendent scenarios it’d help to know what your party is made up of

Thank you, I’ll check that out!

I have a party of four. A black Dragonborn Zealot Barbarian, a High Elf Evoker Wizard, an Infernal Tiefling Aberrant Sorcerer, and an Infernal Tiefling Life Domain Cleric.

I’m currently prepping a mines/cave encounter myself for as early as this weekend.
So far ive got a list of things:
Green slime and brown mold from the dmg.
I’ve got natural gas leaks that cause poison damage if breathed in and ignites if there’s a flame source.
Pitfalls and cave ins.
Umberhulk that’s stalking the party causing them to occasionally take a save vs its confuse ability.

Currently trying to work out a puzzle or two to throw in as well

With so many spellcasters, a room where someone needs to use a spell like detect magic to find the path forward or solve a larger puzzle is a simple but effective way to go.

To follow the “get across the acid moat” idea, maybe it’s more of an acid lake that forces the party to use spells like Tenser’s Floating Disk, Fly, or Levitate to cross. Or if the party doesn’t have spells like that, it may give the Dragonborn a reason to expend their once per long rest use of Draconic Flight to carry the others across or take a rope to the other side

With so many spellcasters, a room where someone needs to use a spell like detect magic to find the path forward or solve a larger puzzle is a simple but effective way to go.

To follow the “get across the acid moat” idea, maybe it’s more of an acid lake that forces the party to use spells like Tenser’s Floating Disk, Fly, or Levitate to cross. Or if the party doesn’t have spells like that, it may give the Dragonborn a reason to expend their once per long rest use of Draconic Flight to carry the others across or take a rope to the other side

With so many spellcasters, a room where someone needs to use a spell like detect magic to find the path forward or solve a larger puzzle is a simple but effective way to go.

To follow the “get across the acid moat” idea, maybe it’s more of an acid lake that forces the party to use spells like Tenser’s Floating Disk, Fly, or Levitate to cross. Or if the party doesn’t have spells like that, it may give the Dragonborn a reason to expend their once per long rest use of Draconic Flight to carry the others across or take a rope to the other side

Thanks so much! These are great ideas!

These are great, thank you!

Yeah, of course! I love creating spaces where players need to use resources outside of combat. Also, sorry about that reply sending twice

No worries, and thanks again!

Also one encounter I’m looking forward to is a room where corpses are dumped after being eaten by something. Gonna have it chock full for carrion crawlers. Those little beasties scare my players whenever they suddenly drop from the ceiling and start paralyzing people. They always say afterwards they need to check the ceilings but they never do…

Check out all the absolute nightmare cave systems we have on earth right now, not just places full of lava, but things like: caves full of odourless toxic gas, or simply with low or no oxygen; caves full of water where simply touching the walls causes the water to silt up so badly you can't see your own hands and lose your sense of direction; massive crevasses that take hours to scale down that require the climber to bend over backwards to keep their footing, and are dangerous with modern climbing equipment; crawl spaces so narrow you can't turn around and have to push your kit ahead of you or drag it behind you, crawl spaces several 1000m from the nearest entrance, where getting stuck won't just kill you but trap everyone in front and behind you in the cave; caves where even the slightest increase in moisture or temperature turns the ceiling and walls to sponge, and risks collapsing the whole structure; invisible lakes of crystal clear water cold enough to cramp you up and drown you in seconds; dead ends; narrow ledges that can only take the weight of one person at a time without crumbling.

Caves are lethal without magic and monsters, combining the above with the kind of underground horrors of dungeon crawling and you can make things truly challenging.

To avoid making things just a skill check or two focus on the tools required to navigate a problem not just the roll required. How could the party scale the ravine, or descend a sinkhole, or squeeze through a crawl space? Make failures increase tension rather than stall it; a failed perception check to find hand holds causes a character to fall and now they're hanging from the rope pulling it taught, the rope is now fraying as its rubbing on the wall, the party only have so much time before it snaps... what do they do?
These ticking clocks keep the tension, and require solutions not just dice rolls, how do they get their friend back to the wall? how do they prevent the rope from breaking? the dice rolls are only there to figure out if their plan works if there's a chance it doesn't.

And for some of these challenges they will solve them without a roll, how do they get their heavy kit across a fragile ledge, a bag of holding. How do they climb to the top of a tall shaft, a rope of climbing, how does the Wizard scale the ravine, a spider climb or a fly spell.

In some of these cases you can add a complication if the pacing isn't working. Everyone having darkvision is great for solving the lack of light, but there's a monster in here that's a real threat thanks to the terrain but it's afraid of bright light but concentrating on light spells means the casters can't concentrate on fly or spider climb.

Hope this all helps.