The Player-Drawn Dungeon Map is a Fast Travel Hack

This post is part of the Prismatic Wasteland blog bandwagon on the topic of maps.

The first mention of mapping by players in the AD&D PHB is on page 101, in the section titled THE ADVENTURE, specifically Dungeon Expeditions:

Here it is explicitly stated that the purpose of the player-drawn dungeon map is to help the party "find [their] way out [of the dungeon] and return for yet more adventuring." There is a tradeoff for mapping the dungeon, which is that movement through the dungeon will be slow. Presumably, this will result in more torches burned, more rations eaten, and more wandering monsters encountered during mapping expeditions.

Just after this, on page 102, we are told that movement through the dungeon is faster when following a map:

Dungeon movement is five times faster when following a previously mapped route. Mapping the dungeon not only allows the players to discern the route back to the surface, but also allows them to move expeditiously along that route (thus reducing the chance of encountering wandering monsters and the use of torches and rations as they retreat).

Page 102 also tells us that mapping is not possible while moving quickly, "such as when pursued or pursuing." Additionally, "light must be available to make or read a map" (infravision doesn't cut it). Marking the walls of the dungeon (as with chalk) or leaving a trail of dropped items or string is "typically useless...as they will be obliterated, moved, or destroyed by passing creatures." The monsters are onto your dirty tricks, and they're here to ensure you end up trapped in the dungeon with them.

The section on MAPPING (page 106) recommends that two players make maps to improve the success of the expedition. It also warns players to "Never become concerned if your map is not exact...As long as it gives your party an idea as to where they are and how to get back, it is serving its purpose."

This coincides neatly with A Knight at the Opera's post on Navigation Games, in which the author argues that an abstracted flowchart-style map which foregoes precise spatial dimensions in favor of relativistic relationships between rooms is the ideal form of mapping in dungeon exploration games.

The most comprehensive remarks on mapping are found in this paragraph under SUCCESSFUL ADVENTURES (page 109):

Here is the crux of the issue: a map ensures that the party will be able to return to the surface. Again it is stated that "Minor mistakes are not very important...so long as the chart allows the group to find its way out!" I will note that the use of the word "chart" calls to mind not a meticulously drafted schematic on graph paper, but something like the flowchart-style map advocated for in A Knight at the Opera's post.

Again it is recommended that two maps be kept in case one is "destroyed by mishap or monster." This is offered alongside sound advice like "In mazes always follow one wall or the other" and things I would never even consider like "[when pursued], always go in a set escape pattern if possible" so your steps can be easily retraced, and "If transported or otherwise lost, begin mapping on a fresh sheet of paper."

That last point brings to mind a room in Dungeon Module B1: In Search of the Unknown in which the party steps into a room and is teleported to another identical room without any indication that they've been transported. I can only imagine the frustration of the hyper-precise graph paper cartographer encountering this room and making a mess of their meticulously measured and sketched map. With a less precise flowchart-style map, the mapper could instead simply add a bubble labeled "teleporting rooms" and connect it to the rest of their chart as they would any other.

In the next paragraph, the value of the map in avoiding encounters with wandering monsters is made explicit:

The map serves another purpose, which is detailed in the following paragraph:

The party is assumed to have an objective, and should not stray from it. "A good referee" will try to distract them from this objective. While it is the party's job to ignore these diversions as much as possible, it is the mapper's job to record their locations so that future expeditions can investigate them. 

The mapper is in many ways the party's memory - they record the dungeon's layout not just so that the party knows where they are and how to quickly escape, but so they know what to come back to. The information they record is instrumental in setting future expedition goals. And, since the party can travel faster through the dungeon along mapped routes, they will be able to quickly make their way back to those diversions on future delves.

Of course, not every one of the DM's nefarious tools can be thwarted by simply ignoring them. The section on TRAPS, TRICKS, AND ENCOUNTERS (page 103) describes traps which confine, channel, injure, or kill characters. Most important to this subject are channeling traps, which include shifting walls and one-way doors. Mapping is suggested as a solution to these traps, as a good map allows the party to find their way back after ending up on the wrong end of one:

The following section on tricks also describes dungeon features which specifically "foul maps", similar to the teleporting rooms in B1:

Let's jump over to the DMG, where the first mention of player mapping is in the section on EXPERT HIRELINGS (page 33):

Specialist scribes (or cartographers) can be hired on a monthly basis to make or copy maps. They demand ten times the fee of a normal scribe, which is 15 gold pieces per month (150 gold pieces per month for a cartographer). Gygax tends to recommend that NPCs charge more to travel somewhere or to provide their services in a dangerous environment, so I imagine that this would be even more expensive if the cartographer is meant to join the party in the dungeon (perhaps five to ten times the usual cost, so 750 to 1,500 gold pieces per month). 

Still, this is well worth the cost if the party can afford it, as they are essentially relieved of the burden of mapping themselves. Instead, I imagine the DM would provide them with a map as they go which, since a well-paid specialist is making it by way of the DM, is probably quite accurate. Of course, a particularly cruel DM is at liberty to take advantage of this by making the cartographer unreliable in some way or by using monsters to target the party's expensive civilian escort.

Note that charmed creatures will not draw maps, per page 43:

If the party wants a dungeon map, they will either have to make it themselves or pay an expensive hireling to do it (and protect said hireling in the process). If they cannot or choose not to circumvent the challenge by paying an NPC, they will themselves have to deal with threats such as traps which channel them into unintended areas and tricks which meddle in their attempts to map. 

We have also been dancing around the issue of time, which imposes the threat of wandering monsters and resource expenditure. So how long does it take to map? The section on THE FIRST DUNGEON ADVENTURE (page 96) gives us some details. This first paragraph suggests that mapping a room or chamber takes 10 minutes:

The next paragraph suggests that each turn, the party can map a length of corridor equal to the party's base movement rate times ten:

Simple enough. However, the first paragraph is contradicted by this next one, which suggests that it takes one turn to map only a 20' x 20' area:

Or perhaps the correct way to read this is that mapping any room or chamber takes one turn, which is the same amount of time it takes to casually examine a 20' x 20' area. I'm not entirely sure.

I tend to let players map one room or chamber per turn. Obviously, this requires stopping in the room or chamber for one turn, so the mapper might update the map while the rest of the party searches the room, checks for secret doors and traps, picks a lock on a door, or whatever. I do kind of like the rule for mapping hallways as I'm never quite sure how to handle those, so maybe I'll keep that one.

There's actually a third way for the players to obtain a map of the dungeon, and that's if they find one. The sample dungeon included in this section of the DMG provides the opportunity for the player characters to find an incomplete map of the dungeon in just the second room:

The importance of this incomplete map is made apparent in the example of play which follows:

The partial map indicates to the players where there might be areas to explore (in this case, they go to Area 3). Since they know that there is an area south of this room, yet there are no exits, they suspect that there must be secret door leading south, and indeed there is.

This, of course, allows the DM to set up an evil trap involving some ghouls:

So maybe if the DM gives you a map of the dungeon in only the second room, be a little wary of where that map might lead!

While there are many benefits and perils when it comes to mapping the dungeon, ultimately the one we must come back to is this: the map helps the party move expeditiously throughout the dungeon. It not only aids the players in remembering the way out of the dungeon, but it hastens them in their egress. The map doesn't just help the players remember things to come back to later, but allows them to return to those side passages more quickly.

Regarding the former - for a player-made dungeon map to yield its true value, getting out of the dungeon without one needs to be every bit as hazardous as making progress into it. This danger is essential to D&D's resource attrition game, which must work as intended in order for the game to remain challenging without relying too heavily on cheap tricks like traps and monsters which can instantly kill the player character. 

One of the most common complaints about D&D's gameplay loop (particularly in post-TSR editions of the game in which all resources are recovered on a single night's sleep) is that the game's attrition-based challenges are too easily circumvented by abusing rests - i.e., the 15-minute adventuring day. This effect is worsened when the DM provides the players with perfect information about the areas of the dungeon they've already explored, such as if the DM draws the map for them as they go, or uses a VTT and leaves previously explored areas of the dungeon displayed on screen after the characters have left them. To rest and recover all their resources, players need only go back the way they came, which is plainly laid out for them by the DM.

If the players have to actually make the map themselves, there's a chance of them doing a poor job. Those who map poorly (or foolishly choose not to map at all) run the risk of getting lost. If they're lost, they can't leave whenever they want to recover lost resources. They may find themselves low on hit points and spells, wandering aimlessly, and easy marks for the dungeons depredations.

The players are rewarded for their efforts not only with hastened escape from the dungeon, but also with expedited travel back into it to tie up those many diversions seeded by the DM on prior expeditions. This allows them to avoid needless encounters with wandering monsters on subsequent delves, making it more likely that returns to the dungeon will be successful and ensuring that the party maintains its momentum throughout the campaign. This doesn't mesh well with modern D&D's dungeons which are seemingly designed to be cleared out in one go, but is essential for making progress in old school D&D's more megalithic underworlds.

The point of the players making the map is to make movement through the dungeon faster, but they have to make it themselves. As argued in A Knight at the Opera's post, mastering the layout of an environment like the dungeon is a perfect example of a challenge of player skill. The map is a powerful tool that must be earned. Don't give it away for free. Or, if you do, be sure to use it to lure the party into an ambush by some ghouls. That'll teach 'em.