Hi guys! I'm DMing my first game for a 5e one shot and the players are all new to D&D. I want to make a puzzle that's not super difficult, but not too easy either. The  only thing is I'm having a hard time coming up with ideas for a puzzle in an underground prison. 

I wanted to introduce them to certain aspects of the game like using skill check for them getting out the cells, then 1 or 2 small combat encounters, and a boss fight to ultimately leave the prison. I want to squeeze a puzzle in to make them think a bit though, so if you guys can help me come up with ideas then that would be very much appreciated!

They're all level 5 and their classes are the following: Warlock, Ranger, Barbarian, Bard, Rogue

Thanks again!

I'm not an expert (building my first campaign). But one of the levels in my dungeon has a prison with a secret tunnel they'd need to find with a survival check, this tunnel would lead to another corridor where a stack of gold lies in a shrine to Nephthys, if they pick the gold, an invisible stalker will attack those that posses such gold (if it is returned and they make an additional offering, it will stop attacking).

You could replace the gold for some weapons in display, so any escaping prisoners would easily fall for that trap, not falling for it would involve investigation checks, arcana or I don't know what else.

Hope it helps.

Once the PCs break out of their cells, maybe the exits seal off and the room begins to fill with sand (water, slime, molasses). There is a keypad in the room that requires a four digit code. The clues for the code may have been found (or still need to be found) in the prison cells. Enter the code before the room fills up with sand (water, whatever).

Here is a video of the puzzle I ran: D&D Puzzle - Escape from Encrypted Sand Crypt

In the puzzle video, the clue to the code is the letter "W". So, in your case, maybe they are in "Cell Block W" of the prison. 

Anyways, hope this helps and good luck running your adventure! Sounds fun!

I would do the classic time limit. "The prison is about to burst into flames! You have an hour to escape!" This tactic rushes things. I know you wanted a puzzle... But wait! If they're taking their time, tra-la-la and all the sudden they explode! They will think of tactical advances, retreats, they'll take combat more seriously, they will strategically maneuver through.

I have found looking at it like a puzzle has gotten me in more trouble than it's worth. In a puzzle we are bound by limitations that are either assumed, implied, or defined for us. In D&D the players have an infinite amount of agency and will use it.

Think of the Truth vs Lie puzzle where one creature lies, the other tells the truth, choose a door based on their answer and you either win or lose. In real live we will assume that the only way to solve the answer is to answer the riddle. In D&D we could cast clairvoyance, we could use familiars, heck we could kill the riddle givers and just search both doors.

With your situation, think of what you want to teach them, and how you can make that a challenge, and then make it so the game mechanics limit their options. This will allow you to imply a puzzle like situation without taking agency from your players. Here's an idea: 

• Skill/ability checks: The players need to figure out what paths the guards use when patrolling, this will allow them to move around the compound without getting caught.
  • Give them a prompt "roll an intelligence" (rolls) "You notice that there seems to be a pattern to the guards' movements, you feel you might be able to use that information".
  • "Give me a survival check please" (rolls) "You see many tracks, however the most recent ones seem to be heading to the left."
  • "Roll perception" (rolls) "You hear the jingling of keys just around the corner, and there's a cough coming from the hall behind you."
  • Then give them a failure, make them get caught, and have them escorted back to their cells. This will show them failure state.
  • Let them try on their own, you've given them the rules, they now have to figure it out.
• Using the environment to proceed forward, teaching to think how anything may be a clue if used properly.
  • The room before the "boss fight" has a mechanism that unlocks the door. Not a key lock but some sort of gear and pulley system that uses weights and counter weights. 
  • Have 3 weights and 3 counterweights, each hidden in a way that complements the character choices. Bard could use a musical instrument to break enchanted glass. Rogue could pick the trapped locker that holds a weight. Ranger could communicate with the rats and have them procure a weight. So on and so forth.
  • Then they have to figure out which weight goes where, each weight is different and they need to have even weights on both sides of the pulley system.

These are very quick thoughts and can be fleshed out further, but I hope they give you some starting points. Good luck with your game and have fun.

A check to see the door would be perception not survival, perception or investigation is used to check if there is something out of the ordinary survival is used for things around the survival knowledge of that character.

hope this helps.

I have a loose designs for a prison which is a retconned from an ancient kingdom (it's set in a place which has been the site of a city for thousands of years, so a 1000 year old lost kingdom being reused as a prison fits). The cells are in the palace, and there turns out to be an escape route which was meant to allow the king to "escape" if things got hot. The tunnel features several traps and such, which are all designed around the idea of delaying the kings pursuers. In one section, they enter a treasure chamber filled with gold bars, with only one exit - a pool of water which turns out to be a tunnel, connecting to another pool.

If they take any of the gold bars, even if they are within a bag of holding etc., then as soon as they enter the water, the gold becomes extremely heavy, and will almost certainly weigh them down and drown them if they don't ditch them. The floor is littered with ancient skeletons of people drowned, all with gold bars on them. The aim is to use greed to kill would-be assassins. 

The tunnel ultimately emerges in a very "lively" tavern. With lots of women employed there. not wearing much. It boasts to be the oldest brothel around, over 1000 years old. I will leave it to the party to realise that's from when the king would have been using this tunnel!

It's worth considering:

 • If there's an escape tunnel, why would it be trapped or such? anyone escaping would focus on escaping.

 • If there's a way to open the doors from inside, why is it there? probably for if the guards forget their keys or some such. People don't build prisons where logical deduction can get you out! "how did he escape?" "Sir he, he solved the riddle and the door opened!". Make the weaknesses make sense - stolen or dropped keys, perhaps a secret knock to overhear, or an overzealous auditor loudly declaims the prison, saying "anyone could climb up that ruin of a wall! get it fixed" where the party can hear.