Sewers are Crazy Dangerous!

[ondonaflash]

So everyone knows that sewers are a common location for adventures. I literally can not think of a single adventure game that does not have at least one section in an urban sewer (if you want to offer examples that contradict this statement please spoiler them at the bottom of your posts), and for the most parts the hazards in these sewers are pretty similar: giant spiders, giant rats, water slows you down, maybe some pits.

And that is actually ignoring a panoply of deadly perils that sewers possess: Most sewers let out into the ocean, which means they flood at high tide! Party goes into the sewer at the wrong time of day? They get murdered by a rushing swell of tide water, or they get dragged out to sea by an invisible, irresistible underwater current! Gas! Sewers are enclosed passages that contain significant amounts of human waste! They are full of toxic, flammable gas! Assuming you don't just suffocate you could blow yourself to kingdom come without any warning! Toshers! People who rake the sewers for valuables! Those probably won't kill your or harm you, but they may be useful as guides, or witnesses in a given campaign!

What other hazards do sewers offer to unwary and unsuspecting adventurers? What other common areas for adventure have hazards which tend to be underestimated?

[chainer1216]

Don't forget the, most likely young adult, ninjas.

[YossarianLives]

Eldritch Horrors are also known to frequent sewers.

[Hyena]

Alligators. You forgot the alligators.

[Cealocanth]

Well, there's the (fairly obvious) filth and disease. Adventurers live dangerous lives. Every hit point they take represents some kind of wound, and even with magical healing, some of these wounds may not heal completely. Furthermore, pretty much every point of damage they will take while in the sewer will open a wound and expose it to a myriad of pathogens, leading to infection. No, it does not make sense from a game design standpoint to make the characters cast Cure Disease every five minutes, but realistically, the adventurers should be dead within hours.

Sewers are cramped. There are main accessways that are barely big enough for an average person to move through without having to duck, but most of the sewer is made of smaller tubes or chambers that must be crawled through. Furthermore, assuming there is a working pipe system (and I don't see why there wouldn't be, even the Romans had something resembling that), there will be sewage pouring from holes in the walls and ceiling at random and unpredictable times. There is virtually no going into a sewer without getting completely coated in sewage.

There are things that grow and live in medieval sewers that could be considered their own ecosystem. Rats are a big part, but those are commonplace. What about crabs, frogs, molds and fungi, and the roots of large plants on the surface? In a fantasy game, imagine the size of the swarms of cockroaches living in these tubes.

Depending on the campaign, the pipes within the sewer may have been made of toxic chemicals. The Romans used lead for their lesser pipes and masonry for their main sections. In addition, everything that is waste to a city was dumped in a sewer in the middle ages (assuming the city had a sewer at all). There could be amalgams of potion waste from alchemist's workshops, poisonous baths from dye workshops, extremely basic waste from tanners, etc. It's not just the disease-ridden sewage that you have to worry about, it's all the other stuff that comes down those pipes too.

Which makes one think; why do so many different kinds of monsters hang out in these places? It would be easier and safer to find a cave or a place in the woods nearby to set up shop. Excluding things like Troglodytes, which thrive on filth, what self-respecting kobold or goblin would choose a sewer over a nice, dank cave, or a secluded clearing?

[PersonMan]

Probably none. :smalltongue:

The issue is: do they have a choice? I can see a few goblins or kobolds trying to hide in the tunnels beneath a city in a desperate attempt to find somewhere to live that's not filled with people trying to kill them.

[dramatic flare]

And that is actually ignoring a panoply of deadly perils that sewers possess: Most sewers let out into the ocean, which means they flood at high tide!

Most sewers don't do this, precisely because it would back up the sewer system and "Literal crap explosion," would happen anytime someone flushed/otherwise released pressure on the back-up. We know this because Seattle accidentally did this once during their history.
Though I suppose if the sewers are big enough for humans and monsters to fight in, it's probably big enough to handle some flooding.

[Actana]

One common theme I seem to recall somewhere is that in larger fantasy cities, the sewers are actually the remains of previous buildings and ruins that the current city was built upon. Slightly restructured so it works as a sewage system but otherwise left to its own devices, the entire sewer network could change immediately if this sort of approach would be taken. A sort of undercity vibe, where those despondent and downtrodden end up in the less ruined buildings and gather into small communities for safety, while the darker corners hold all sorts of creatures. Essentially, instead of an absurdly large sewer, you'd have a ruined built upon ancient city.

[Tvtyrant]

One common theme I seem to recall somewhere is that in larger fantasy cities, the sewers are actually the remains of previous buildings and ruins that the current city was built upon. Slightly restructured so it works as a sewage system but otherwise left to its own devices, the entire sewer network could change immediately if this sort of approach would be taken. A sort of undercity vibe, where those despondent and downtrodden end up in the less ruined buildings and gather into small communities for safety, while the darker corners hold all sorts of creatures. Essentially, instead of an absurdly large sewer, you'd have a ruined built upon ancient city.
This is the Futurama/Ank Morpork approach. The problem with an undercity is explaining why the ground doesn't collapse.

[Gritmonger]

This is the Futurama/Ank Morpork approach. The problem with an undercity is explaining why the ground doesn't collapse.

*Pffft* That's just a sub-urban legend.

[sktarq]

Sewers make a great place and classic place for thieves - possibly connecting to their guildhouses. There is even precedent for this in places like Paris where the sewers were used by the criminal class - largely as a transit system to connect to the undercity places they wished but it makes for a good base for fantasy

Also undead are pretty comfy in such places too. No need to worry about disease, food needs, good quality air, etc. Also if the undead are being controlled it is a good way to move them around an inhabited region to get close to targets with low chances for being discovered or eliminated. - to a lesser extent this applies to constructs as well but those are often single high value/potent creatures while undead are often bulk troops who have fewer options.

also Otyugh, neo-otyugh etc were created for sewer systems, basically so they need to be put on this list

[Dimers]

Deranged but brutally cunning serial killers.

Oozes.

Gates to the underworld.

Or the entire sewer system is sentient as a whole -- even sapient. Its whole existence is toxic, it is sick to death of dealing with the upperworld's wastes, and it will snap if just one more goddamn adventurer comes down here to kill a kobold ...

"Vilmar, as the Rat King's blood arcs off your blade, you hear a moan from all around you, a terrible shaking moan that quickly builds to the skull-transcending level of a dire lion's roar. The walls and floor start to buckle and ripple, so everybody roll Reflex, DC 26, or you're knocked prone. Rust and dried filth fall from the pipes overhead, and the only exit you see -- the same little tunnel you crawled in through -- squeezes closed as if it were some humongous intestine. Your torches are dimmed by some unnatural effect, but there's still just enough light to see gray-green muck start to bubble out from the grates in the floor. What? -- no, that was just its first round, you haven't had time to react yet. Wait for your turn in initiative."

[Arbane]

Girl Genius has a few things to say (http://www.girlgeniusonline.com/comic.php?date=20060501#.VQT0FuF0apo) on the topic of sewer ecology.
http://www.girlgeniusonline.com/ggmain/strips/ggmain20060501.jpg

[(Un)Inspired]

Turd Golems and toilet-flushed alligators.

Myst

[Tommy_Dude]

Well for your more gritty/realistic sewers, yes, waste from different buildings, gasses natural or otherwise, theives, diseases, mold and fungi, and assuming there is enough room for a person to walk you also have to watch out for any semblance of purification machinery. From sluice gates that activated based on water level to more modern equipment depending on your setting. On top of that (this may not be true but I haven't slept in two days so don't correct me, I'll correct myself later :P) if the sewers were enough to walk in you'd have the odd danger of running into social outcasts such as lepers or beggars who would get chased from "proper" places like alleys by the city watch.

For a more fantasy bent, as others have said undead are great. I would like to add, however, leech swarms, maggot swarms, biting fly swarms, rust monsters, otyughs, certain carnivorous plants, anything with disease immunity that you think would make sense. Following the leper idea, beggars and sick people who are actually Were-Rats, or other forms of lycanthropy. Any creature who dwells in ruins would also make sense. If your city is at least advanced enough for a steamworks or heated pipes then you have pipe burst dangers, well you also have pipe burst dangers if the sewage overflows too much. Will o Wisps I would think live in sewers if society encroached too much. As far as to why Kobolds live in sewers? They usually don't in my mind, but sometimes their expansive cave tunnels break into the sewers and then cause issues for them and the town.

The only other dangers I can think of right now, due to exhaustion is that honestly? Without a map? Getting lost. Also no natural lighting if your torches run out. Many older sewers only had a few entrances because no one expected to work on them much. At least at street level, and if dealing with a particularly crafty Zombie Lord Necromancer, he may even cast Maze on you to fuddle things further.

[gom jabbarwocky]

Sewers smell nasty. There should be a few penalties for dealing with the intense stench. There's also infection, but in most games that's no fun; you're not playing Diseases & Dysentery, I presume. Still, there's that risk. Also, sudden drops concealed underwater, floodgates, and rabid animals are all potential sewer threats. Also, don't forget the possibility of C.H.U.D.s, Morlocks, and other cryptids.

Some older cities have, in addition to sewer systems, catacombs. All kinds of creepy fun to be had there.

I ran an oWoD game where the old Nosferatu Prince got bumped off when someone flooded the sewers and he got washed out - the sun took care of the rest.

[SiuiS]

This is the Futurama/Ank Morpork approach. The problem with an undercity is explaining why the ground doesn't collapse.

"Poppycock!" Says the giant, his eighteen foot bulk supported by a wooden house carved out of 10"x10"s. "Your square cube law is a silly humanocentric fallacy that doesn't hold up in this world of spell travel and talking eye tyrants!"

[Tvtyrant]

"Poppycock!" Says the giant, his eighteen foot bulk supported by a wooden house carved out of 10"x10"s. "Your square cube law is a silly humanocentric fallacy that doesn't hold up in this world of spell travel and talking eye tyrants!"

That would explain the colossal bugs running around. Or surface areas get stronger when covering more area?

[Gritmonger]

That would explain the colossal bugs running around. Or surface areas get stronger when covering more area?
Of course, which is why a fully inflated balloon is like iron armor. Science!

[Mr Beer]

Cramped and impassable pipes, lack of light, getting lost, getting drowned, getting suffocated and getting some vile infection are probably the most realistic problems with sewers, along with the stench and general ick factor of being covered in raw sewage and all the other liquid and/or floatable refuse that a quasi-mediaeval city has to offer.

[Gritmonger]

Ick factor is why I prefer storm sewers - that and they tend to be larger to handle sudden large volumes of water rather than a steady treacle. Tinkle. Trickle.

I'll stop talking now.

[Tvtyrant]

Ick factor is why I prefer storm sewers - that and they tend to be larger to handle sudden large volumes of water rather than a steady treacle. Tinkle. Trickle.

I'll stop talking now.

I had to look up storm sewer to find out what you were talking about. Yay dialects!

[Maglubiyet]

I had to look up storm sewer to find out what you were talking about. Yay dialects!

Yeah, we call those storm drains. Spent my childhood exploring them. I even considered writing my undergrad thesis on the ecology of them in my region.

We never saw any rats in there, but plenty of raccoon tracks. Thinking back on it, it was nuts -- we used to squirm through some of those things on our bellies.

EDIT: Just for edification, our sewers do not empty into our storm drains. They are two entirely separate systems of tunnels.

[Gritmonger]

Yeah, we call those storm drains. Spent my childhood exploring them. I even considered writing my undergrad thesis on the ecology of them in my region.

We never saw any rats in there, but plenty of raccoon tracks. Thinking back on it, it was nuts -- we used to squirm through some of those things on our bellies.

EDIT: Just for edification, our sewers do not empty into our storm drains. They are two entirely separate systems of tunnels.

Yeah, a Storm sewer is separate from the actual sewage system - and was instituted to keep a combined system from overflowing or backflowing in heavy rain.

[ondonaflash]

Yeah, a Storm sewer is separate from the actual sewage system - and was instituted to keep a combined system from overflowing or backflowing in heavy rain.

Which brings to mind that sewers could become incredibly dangerous in the rain! So bring in weather as a perpetual hazard while exploring sewers...

[Maglubiyet]

Which brings to mind that sewers could become incredibly dangerous in the rain! So bring in weather as a perpetual hazard while exploring sewers...

Most modern sewers are separate systems from stormwater management and aren't prone to flooding in mild to moderate rains. In severe flooding, the sewers can take on rain water or the sewage treatment plant can flood, spilling raw sewage into waterways. In older systems (like probably most fantasy worlds) sewage and rainwater go to the same place.

Being in a drain pipe in the rain is an incredibly BAD idea! When I was a kid, a friend and I went into a tunnel about 20 - 30 minutes after a light rain started. The water level hadn't risen at all so we thought everything was okay. We got a good 200m when we saw something moving up ahead. It looked like a big animal so we stopped and were trying to make it out with our flashlights.

Turned out it was a big pile of debris riding the crest of a storm surge, a small wall of water 4 or 5 inches high. Doesn't sound like much, but even 4 inches can knock you off your feet. There had been a time delay from the start of the rain to when it hit the tunnels. By the time we ran back to the entrance the little trickle in the pipe had expanded to fill any dry walking space and was more than 6 inches deep. I got out okay with wet feet, but my friend was on the other side of the stream and couldn't get up the embankment on his side. He had to take a little swim to get back to my side. This definitely could've turned deadly, but fortunately the gods favor the stupid.

I wouldn't want to be in a sewer crawl, hunting giant rats and zombies, when a thuderstorm hit. Depending on the accessibility of the system, you might not have any idea it was raining until it was too late. The denizens might know, though. That's an awesome idea, have the PC's fighting sewer critters, when suddenly all of the giant beasts turn and run away because they sense the floods coming. The characters are left standing in the silence, wondering "what the..."

[SiuiS]

Of course, which is why a fully inflated balloon is like iron armor. Science!

*looks at the spore balloon that's designed to look like a beholder, armor and all*

Seems legit.

[Joe the Rat]

Ick factor is why I prefer storm sewers - that and they tend to be larger to handle sudden large volumes of water rather than a steady treacle. Tinkle. Trickle.

I'll stop talking now.

The architecture of most "sewer levels" is really more reminiscent of a storm drain system than a sanitation system, but that doesn't prevent the two from being combined. Though it is taking cues from the Roman systems as well. In which case you should add lead poisoning to the list of hazards. :smallwink:

[ondonaflash]

One of my favorite tricks from White Plume mountain was to have the floor be covered by murky water, and then have a pit below water level that could not be seen. And just because I'm not particularly nice, I see no reason why that pit shouldn't also have spikes!

[Arbane]

Though it is taking cues from the Roman systems as well. In which case you should add lead poisoning to the list of hazards. :smallwink:

If you're licking anything in a sewer, you're going to have much bigger, more immediate problems than lead poisoning. :smallyuk:

[Tvtyrant]

I'm currently working on a gigadungeon sewer inspired by this thread. A ln abandoned dwarven mountain hold (the mines petered out) now has a human city over it. The city uses Decanters of endless water to flush the city streets down storm drains leading to the 1,000 ft deep elevator shaft in the mine. As the mountain slowly fills with waste a crisis is building up.

[PersonMan]

One of my favorite tricks from White Plume mountain was to have the floor be covered by murky water, and then have a pit below water level that could not be seen. And just because I'm not particularly nice, I see no reason why that pit shouldn't also have spikes!

Wouldn't that only work if it was a shallow pit? Otherwise people would just fall and be swimming.

[ondonaflash]

Wouldn't that only work if it was a shallow pit? Otherwise people would just fall and be swimming.

Only if the person leading the party isn't the one in the heaviest armor.