I have a player who climbed down a 50-foot ravine via rope who was ambushed by a few swarms of rats as soon as she reached the ground.  The rest of the players did not follow along so they are at the edge of the ravine looking down.  This is where the game session ended-- on a cliffhanger.  Bad puns, ok, really bad puns aside the players are now strategizing their next move two of the characters want to climb down the rope to help out.  (Yes, the player at the bottom of the ravine 'could' climb back up the rope and take a possible OA or two but that thought has not been brought up yet.

I know climbing regardless of direction takes half the players' movement but I was not sure if that was for just in a free climbing sense.  If not and doing the climbing math it will take the players, roughly four rounds to reach the bottom of the ravine which may not be the best use of their time.  

So was wondering 1) do I have my climb math correct and 2) does a rope add any benefit to speed if they were moving down a wall or regardless of what may be assisting the player it's still half movement. 

Quote from BKThomson >>

I have a player who climbed down a 50-foot ravine via rope who was ambushed by a few swarms of rats as soon as she reached the ground.  The rest of the players did not follow along so they are at the edge of the ravine looking down.  This is where the game session ended-- on a cliffhanger.  Bad puns, ok, really bad puns aside the players are now strategizing their next move two of the characters want to climb down the rope to help out.  (Yes, the player at the bottom of the ravine 'could' climb back up the rope and take a possible OA or two but that thought has not been brought up yet.

I know climbing regardless of direction takes half the players' movement but I was not sure if that was for just in a free climbing sense.  If not and doing the climbing math it will take the players, roughly four rounds to reach the bottom of the ravine which may not be the best use of their time.  

So was wondering 1) do I have my climb math correct and 2) does a rope add any benefit to speed if they were moving down a wall or regardless of what may be assisting the player it's still half movement. 

  

 Yes, they do not have to make a skill check to climb down.

Would up be any difference and not require a check

Yes, climbing is half speed. Not "climbing up", not "climbing rocks", "climbing." If your players are "climbing down the rope," they are climbing, and would move at half speed (as you said, 4 rounds or 24 seconds to climb down a 50 foot rope). But, that isn't to say they can't "Dash" to climb 15x2 per round, potentially only taking two rounds (12 seconds) to go down, which sounds more than reasonable.

If they want a quicker way down, might I suggest "jumping" or "falling"? In all seriousness, falling only does 1d6 damage per 10 feet, so may not be a totally bad idea for characters that are 10-20 feet off the ground and don't feel like wasting a second round of climbing. "High Jumping" to move down is poorly defined in the PHB, but the way I've always played it is that you can move your High Jump distance in either direction vertically before you're "falling," so even without a running start, a jump+fall combo should be enough to let most characters drop 10-15 feet without harm instantly. 

I can't find any "official" 5e mechanic for climbing a mundane rope, so I assume it falls into the category of DM discretion.

Other editions offer charts for Climbing difficulty, including:

• DC 15 (unknotted rope)
• DC 5 (knotted rope, or unknotted rope with a wall to brace against)
• DC 0 (knotted rope with a wall to brace against)

 This check is for both up and down.

The fastest way to go down a cliff, is to fall. However, with a rope, they could reasonably attempt a slow fall.

I would recommend allowing the players to rappel at full movement speed at a -5 penalty to their check.

Thanks, everyone for the information.  I appreciate it.

Alternatively, the player at the bottom could grab the rope and the rest pull the rope up? Because, if pulled up, they wouldn't suffer AoO, because they aren't using their movement to move out of reach.

But yeah, I think rope just means you should consider being easier on the skill checks (if you feel like they need to make them)

All climbing cost double movement unless you have a climbing speed. How you climb doesn’t matter. 
If your PCs move 30 feet they can dash with their action and movement to climb 30 feet on their turn and could get down in 2 turns. Rogue or monk that can dash as a bonus action could climb 45 ft on their turn and just let go to drop the last 5 to do it in 1 turn. 

I couldn’t find rope climbing DC anywhere either. Thought it was listed somewhere. Normally I don’t have PC’s roll skills to climb a rope. Unless they are being attacked or it’s raining or icy or something. But if you want them to make a skill check:

The basic DCs given in the DMG are as follows:

-So pick how hard you think it would be to climb that rope and use the corresponding DC. If it was a knotted rope I’d give advantage like a rope of climbing. DC 15 feels right. Moderately Difficult. If they succeed they can move. If they fail the check they make no progress that turn, if they fail by more than 5 they fall.

—You could also have them do a group check if they are all climbing down together. Help compensate for PC with low Strength or Athletics.

If they have a reasonable level Barb, or any character with >60ish HP, I would be tempted to just jump down if I was one of them. Even RAW (I'd subtract their high jump distance from the fall if they are purposely jumping, although I don't think that's RAW), 5D6 damage is about 18HP average, 30 max (halved to 9/15 if a Barb rages)... That's not much unless the party is pretty low level. Personally, I might allow them to stand up from prone after doing so on a check/saving throw with a DC equal to the amount of damage taken, although that would be the end of their turn.

For climbing, yes, I would say they can automatically move half their movement speed (without a check), and would be perfectly at liberty to Dash to travel the same again up or down the rope. If they want to improve on that, I would ask for a Strength/Athletics or Dex/Acrobatics check (depending on how they want to extend the distance). The first character to do so, I'd make fairly easy, but any more it would get difficult (due to others being in the way). I think, on a success, I'd allow them to add something like half their Str/Dex score (depending on which they used) to their speed (so, for a 30ft character with 12 Str, they could climb 21ft using just movement or 41ft dashing).

Oh, and if the player decides to climb back up.... I would have the swarms follow him up. Rats are really good at climbing (although RAW they don't have a climbing speed for some reason). They should at least keep up with him, which could well give an OA on the second turn too. I would, personally, be tempted to say the swarm does have a climbing speed and can follow him, biting at his heels, all the way up. Start singing about how bravely he looked running away while you're at it lol.

Quote from UrthTheThoughtless>>

At the time the player reminded me that she had tied the rope around her waist so when she climbed back up to avoid the Swarm she carried the rope with her. 

The encounter turned out to less of an encounter because the Warlock and Wizard at the lip of the ravine cast Shatter and Ice Knife and was able to blow away four out of the six swarms in one go.  From there I decided that after a Thunder Boom and Ice Shards it was enough to have the remaining Swarms to run away.  

I am not saying your wrong, But it is probably the dumbest thing I've heard. Ask rock climbers or special forces operators (which they could  fast rope down 50 ft. in about a second). how does one argue that climbing the wall takes the same amount of time as scaling a wall?

As a DM i only ask for a Strenght (Athletic) check to climb when a condition are challenging somehow, such as when a player character attempt to climb a sheer or slippery cliff, and or to avoid hazards or interference while doing so. Sheer being something extremely steep or almost vertical, i interpret climbing a rope vertically to be the case.

But in non-stress or urgent situation, i tend to not ask any check to climb using a rope, unless the distance is significant. It all comes down to wether i want any given climbing to be a challenge or not.

Quote from Plaguescarred >>

As a DM i only ask for a Strenght (Athletic) check to climb when a condition are challenging somehow, such as when a player character attempt to climb a sheer or slippery cliff, and or to avoid hazards or interference while doing so. Sheer being something extremely steep or almost vertical, i interpret climbing a rope vertically to be the case.

But in non-stress or urgent situation, i tend to not ask any check to climb using a rope, unless the distance is significant. It all comes down to wether i want any given climbing to be a challenge or not.

 Wow, this was a two-year-old post and what I know now compared to when it was written is pretty significant, but I agree and have followed that same rule of thought when it comes to climbing as you do.

Quote from Nurnick >>

I am not saying your wrong, But it is probably the dumbest thing I've heard. Ask rock climbers or special forces operators (which they could  fast rope down 50 ft. in about a second). how does one argue that climbing the wall takes the same amount of time as scaling a wall?

Those people you're referring to are rappelling down, not climbing down.  You'd simulate this in 5E by having a climber use their item interaction(s) to manipulate the rope to let you fall a controlled distance; as Chicken_Champ mentioned, the rules for jumping downward are poorly defined, but it's certainly within what little RAW we have for jump distance to subtract from fall distance for calculating fall damage.  Furthermore, we only have rules for taking falling damage when you land on something that arrests your fall - a rope-arrested fall is in the rules (that's how the pitons in the PHB work), but we have no basis for guessing intended falling damage from it.  All of the following is within strict RAW for a 30' speed climber with no climb speed avoiding all falling damage, assuming a rope-arrested fall simply does full falling damage:

• Jumping down is impossible (this will tend to kill jumping-based creatures, like giant frogs, so it may be an unlikely ruling):  Dash to be able to climb down 30' with your move, move down 30', free item interaction to coil up 5' of rope, economy-less to fall 5'.  End 35' down, 15' above the ground.
• As above but jumping down is well-defined in the way C_C described, climbers are Str modifier -2 to +2:  As above, but your fall at the end is a high jump and then a fall totaling 10' but not dealing any damage because you soaked more than 0 feet of the fall.  End 40' down, 10' above the ground.
• As above but Str modifier +3 to +7:  Your coiled rope fall is now 15' because your high jump is good enough to reduce the fall to 0 damage.  Because this ends 5' above the ground, you can follow up with a normal fall and land on the ground.
• As above but Str modifier +8+: Your coiled rope fall can be 20' and you land on the ground.
• The jumping rules say your DM can let you roll Athletics to jump higher/farther and then stop talking, so there's no way to rationally discuss options here, but certainly it's well within the RAW for your DM to let you combine any of the above 3 bullet points with rolling an Athletics check for additional distance.
• Naturally, a climb speed (like rangers and druids have easy access to), being able to Dash as a bonus action (like rogues), and being able to just fall safely (like monks) can all make rappelling even easier, depending on how you want to interpret special forces training.
  • The above can potentially be combined with grappling an ally and carrying them over the cliff with you, like the climbing in The Princess Bride.