Depth Tolerance

[Naanomi]

What would people guess is the depth tolerance of a Water Genasi? A player in my campaign wants to build a personal underwater base 'as deep as she can stand it', but not sure exactly how deep that might be. Opinions?

[Toadkiller]

In general it is the speed at which a marine animal gains or loses depth that is ths bigger issue. Deep sea fish can be killed by rapidly pulling them to the surface. So, you can likely put a limit of a couple hundred feet and say something like "any deeper and it isn't practical to come and go easily." Also,much beyond 100 feet and it gets dark and cold.

[Naanomi]

Cold is a good point. Light can be fixed with permanent magic, but cold is tougher to solve I think. Still, magic might presumably find a way around the temperature too, but depth is part of the appeal: good defense against folks teleporting in if they get crushed at pressures your partially-water-elemental body can stand

[Daishain]

True depth tolerance is difficult to determine. The human body is already capable of withstanding pressures that would crush a submarine, so long as said body is properly acclimated and the air in the lungs is at the same pressure. A water genasi wouldn't actually do much better than a standard human in that sense, although they'd need less help getting to that brink.

The real issue is transition, getting to and from high pressure areas too swiftly can be quite deadly, even for creatures that do so on a regular basis.

But let's say you've worked your own transport out and are just trying to figure out how deep you need to go to discourage visitors. 100 meters is more than enough to discourage divers without supplied air (yes modern divers have gone further, but that was with mechanical assistance to speed up the trip). 300 meters would be sufficient to discourage divers with supplied air or simple sub devices like the apparatus of Kwalesh, and that's if they figured out how to deal with O2 toxicity at pressure, if not, they start having issues at about 50 meters. As for teleporters, supplied air or not, going up or down just 100 meters without a transition phase would be excruciating and cause damage to the body. 200 meters might kill.

I'd say 3-400 meters down would be quite sufficient. A determined individual with enough resources could still reach you, but that remains true past the point where it would be easier to build a base on the moon. 100 meters would be a lot easier to deal with so far as having a livable home base goes, though it does slightly increase the risk of intruders.

If he's determined to go as far down as possible, several kilometers should be doable, although pinning down an exact depth is going to be difficult. We have little data on long term human survival that far down.

[Naanomi]

Air in the lungs shouldn't be a problem, Water Genasi magically breath water so being ready with practice to exhale should do the trick. They also have acid resistance so appropriately toxic water might be helpful from a defense standpoint.

Oh and Hallow can be made perminant and be set to protect against cold

And yes, deep as possible is the goal I think... Wants to be down there next to his Old One masters at the bottom of the sea and all

[MrStabby]

Most of the issues with pressure are about how gasses behave. With incompressible water being breathed they are basically aquatic. The low number of vertibrates at high depths is not so much due to pressure as due to food scarcity (need really slow metabolism and you basically eat the dead crap that falls from above).

As pointed out the pressure change is a bigger deal with getting in and out but as a long term place for downtime it could work.

[Ralanr]

Air in the lungs shouldn't be a problem, Water Genasi magically breath water so being ready with practice to exhale should do the trick. They also have acid resistance so appropriately toxic water might be helpful from a defense standpoint.

Oh and Hallow can be made perminant and be set to protect against cold

And yes, deep as possible is the goal I think... Wants to be down there next to his Old One masters at the bottom of the sea and all

How would he even see down there? Do water Genasi have darkvision?

Then again, sounds like a warlock. So the darkvision isn't a problem. Is he just swimming up and down from this place or is it teleportation based? Since they have a max of 30 feet movement, that's about 10 feet a second if they're dashing. Even if that's only combat it would still take a long time from what I understand to hit deep ocean waters. And if he's coming right back up you'd have to worry about decompression sickness.

Is realism important? I mean this is a half water elemental person whose race as a whole is probably faster than Olympic swimmers (I don't know off the top of my head) we are talking about here.

[cobaltstarfire]

Cold is a good point. Light can be fixed with permanent magic, but cold is tougher to solve I think.

Not that tough, if they're going to the bottom of somewhere, just find some thermal vents to settle near.

[Daishain]

Not that tough, if they're going to the bottom of somewhere, just find some thermal vents to settle near.
That's more difficult than you might think. The temperatures near thermal vents go from hot enough to boil you in your skin to cold enough to kill within a matter of inches. The energy to be found there certainly could be harnessed, but it would take very careful engineering design to create a living space that takes advantage of it in that way.

[MrStabby]

That's more difficult than you might think. The temperatures near thermal vents go from hot enough to boil you in your skin to cold enough to kill within a matter of inches. The energy to be found there certainly could be harnessed, but it would take very careful engineering design to create a living space that takes advantage of it in that way.

I think thermal vents dont heat the surrounding area much due to a kind of chimney effect. The hot water rises pretty fast and sucks in cold. Even just forcing it to circulate a bit around the room would take the chill off it.

Make the walls out of stone, not metal and I think you should be ok.

[Naanomi]

Yeah I think she will use hallow to deal with temperature, but might look for vents to have acidic water about.

[charcoalninja]

I'd personally use Whales as a metric. They submerge and surface continually but still can reach incredible depths, and they breath air not water. Seems a good compromise for something mammelish but at home in the water, and would be more than deep enough to make it crazy freaking dangerous to try to mess with your waterhome.

Some whales can go as far as 3km below the surface for example, so you have a lot of room to work with.

[Naanomi]

Which would be about 3km down? About halfway down the 'normal' ocean depths? Triple the depth of a submarine, but not quite as deep as the titanic? Nowhere near the traditional 'deep sea weird fish'?

[Shining Wrath]

I think you should just handwave away the bends and similar pressure change effects from traveling up and down. It's magic, after all.

There is no limit if they only teleport in and out. Light and temperature can be dealt with by magic; pressure differences are accounted for by exhaling just as you teleport (which makes a wonderful built-in trap for those who don't know that).

If they've got to swim, swimming for 5 miles in complete blackness can pose a problem; being the only thing carrying a light in complete darkness ought to pose a much larger problem.

[Easy_Lee]

I think you should just handwave away the bends and similar pressure change effects from traveling up and down. It's magic, after all.

There is no limit if they only teleport in and out. Light and temperature can be dealt with by magic; pressure differences are accounted for by exhaling just as you teleport (which makes a wonderful built-in trap for those who don't know that).

If they've got to swim, swimming for 5 miles in complete blackness can pose a problem; being the only thing carrying a light in complete darkness ought to pose a much larger problem.

I agree with this. Pressure and the bends are some unfortunate facts of real life that the D&D gods ought to handwave away. And who knows what terrifying sea monsters lurk in the oceans of Faerun...


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[Naanomi]

Some of those look like they might get along fine with an Old One Warlock living in the depths. Sahaugin, water elemental creatures, Atlantean golems though.... Kraken... May need some protection from them set up

[Camman1984]

I think if you apply any kind of realism to it it becomes impossible. look how difficult it is for us to go that deep and we are way ahead of dnd technologically.

with magic on the otherhand, anything is possible. my solution, rather than have him summon up the necessary skills to build it himself, which i think leads to all the problems associated with it. How about he finds vague rumours of an ancient temple dedicated to an appropriate sea god where priests used long forgotten epic magic to make it habitable you could also throw in a surface teleporter that can only be brought back to life with the right rituals, maybe spells such as underwater breathing, protection from elements etc all cast in the right order. That gives you a plot device for a quest, along with enough room to hand wave the practicalities of underwater living.

"Ancient forgotten magics" make an excellent plot device without giving the players the tools that could drastically affect your world's balance.