Query for you all. I'm currently running Dungeon of the Mad Mage for my Twitch channel and well, how do y'all recommend I make the adventure more thrilling, description wise instead of just guiding them down tunnels? A lot of the adventure so far has been the party walking down long corridors and me describing the turns and corridors ahead of them. It gets more interesting when they find actual rooms with detail and purpose, but the corridor stuff is really...something and I find myself trying to rush through the long bits of corridor. There's a lot of empty corridors in Mad Mage.

I've always struggled with making dungeon delves thrilling in a narrative/roleplay aspect.

The book/maps don't exactly provide a lot of descriptive text for the rooms, which bums me out. Should I just go with improvising little details? I'm comfortable doing my own thing and what-not if I've built the dungeons myself, but I've been struggling with this adventure. I love Mad Mage, and my group has been having fun (it seems) and I just want a little bit more of that immersive flair added to the sessions.

Maybe I should do more of wandering monster suggestions in the book for each floor? We're currently only on the Arcane Chambers floor (second level) of the dungeon.

I like to think on the elder scrolls for when I try to make underground things more interesting. Try to incorporate some kind of terrain type like where they entered. A sunken in roof to a giant cavern, over grown root system covering a spot like that. Huge split in the earth which falls much deeper. Unground spires leading threw cut outs of earth. As far as what’s in that room, or areas. I make 3-5 big rooms that serve purposes. Soldiers barracks, mages research lab, magical forge etc. And then make surrounding areas support areas for that purpose. Soldiers need weapons, armor, food. Mages need resources, books, testing equipment... so on so forth. And more or less big rooms can be added obviously. 

Hopefully this helps?

I know what you mean. I remember DMing a group through the original dungeon and there were just far too many rooms without description to fill. It became stressful for me and boring for the group.

Thrown in a scary reoccurring monster or villain that just appears from time to time. It could be a shadow/specter/wraith/ghost that appears out of the walls to attack before retreating. Get the party questioning why it is attacking them? Why is it retreating? Is their any warning signs before it appears?

Traps are a great way to make boring corridors more interesting too. Just another average hallway...until a pit opens up or the roof collapses.

What about strange magical symbols appearing in otherwise empty rooms. What do they mean and say? Perhaps this mystery is revealed when they find a tome, statue or carving elsewhere.

Do they have a day to find something before magical doors begin to close or monsters start to be released? Perhaps those empty rooms begin to have monster randomly teleport in.

Good luck

As they are a walking, there may be corpses or traps along the way. You can try to make it a bit more visceral by explaining the sounds echoing in the distance as they walk, the smells of the corpses they're walking past that are long dead, the inscriptions on the walls or traps that spring as they are simply running through a long corridor that they didn't notice. The feeling of the ground beneath their feet may change, which can allude to traps below, or perhaps water sources nearby as the earth is softer with each step.

If you can make the players feel as if they are there with your descriptions which hit the 5 senses, even simply walking down a random corridor can be exciting.

A good detailed description of the dungeons and caverns is a must but also consider diving into all senses, like smell, taste sounds and what they see i.e. "You walk further into the dark, cold caverns. you hear the slow drips of water from the stalactites above. drip...drip.. echoing through the caverns, the smell of stale water and sweat as your slowly progress with your companions. You feel the humid air causing your clothes and armor to stick to you like a second skin" just spice it up remembering that they rely on you to know whats around them. subtle things like "the smell of ozone" could warn or some electric/lighting threat, or a metallic taste in the air could help drive their imaginations. hope this helps !

There's some good advice in one of the earlier books about Undermountain (the 3e one I think) where it says to foreshadow things that are around. You can keep these things for if the players use perception or investigate (if they're doing that) or just reward them with bits of information if they have a decent passive perception. For instance if there's a gelatinous cube around you'd probably note that the hallways seem unusually clean, free of dust and debris. If there's an aboleth nearby the stonework is slimy and slippery (enough to be difficult terrain if it's near the lair). Maybe they find the droppings of a creature that lives nearby and someone proficient in Survival can Survival check to determine what sort of thing it is (provided they're willing to get their hands dirty). The 3e book gives the example that some creatures are leading a large slug around and it's leaving a slime trail around the dungeon, and perceptive enough characters can notice the dried slime on some of the walls and floors. These sorts of things reward perception and investigation checks without having to always say there's nothing there or give out too much treasure.

Wandering monsters are a good idea.  You can also have non-monster animals show up from time to time.  What kinds of real-life animals would inhabit a dungeon?    Not all spiders have to be large enough to threaten adventurers, but their webbing could nevertheless provide partial cover.  Also, what kinds of fungi would live there?  Put a shrieker in a few of the passageways and make your characters more wary of even mundane things.  Millipedes, rats, etc.

If you have a large, low-intelligence monster in a pre-determined room, there might be tailings of some kind a few rooms or passages away.  Monster dung?  A femur or a skull?  A normal shield or dagger left over by a previous adventurer?  

 My players just got to the third floor on Wednesday. The Sargauth level of Undermountain.

Seems to be more "open" now if that makes sense and less dungeon crawly. I'm excited to see if my grievances with the first two floors are somewhat reduced now.

Thanks for all the tips everyone!