Someone on RPG.net just made a reference to an Ocean World made almost entirely of water. Like water all the way through, with no rocky bit in the middle.

Seems you might end up with a planet completely covered by an ocean hundreds of kilometers deep, over a core of ice made solid by the (immense) pressure of water above. And the ice might be an exotic form of ice with the enticing name of Ice VII.

http://en.wikipedia.org/wiki/Ocean_planet

http://en.wikipedia.org/wiki/Ice_VII

Sounds like a good place to meet new and interesting people... and kill them.

And someone else mentioned Ice Nine -

+++++ Ice-nine is a fictional material appearing in Kurt Vonnegut 's novel Cat's Cradle . It is supposed to be a more stable polymorph of water than common ice ( Ice I _h ) which instead of melting at 0 degrees Celsius (32 degrees Fahrenheit), melts at 45.8 °C (114.4 °F). When ice-nine comes into contact with liquid water below 45.8 °C (which is thus effectively supercooled ), it acts as a seed crystal , and causes the solidification of the entire body of water which quickly crystallizes as ice-nine. A global catastrophe involving freezing the Earth's oceans by simple contact with ice-nine is used as a plot device in Vonnegut's novel.+++++

We could certainly speculate that a core of Ice-Nin e exists at the center of one of these planets, and the Adeptus-Mechanicus, and other factions, become engaged in a race to harvest it for their own nefarious purposes (freezing worlds for instance).

And lets not forget the neferious Xenos on the planet who will give the arriving Imperials a frosty welcome.

Sounds like this could be a pretty fun game with alot of un-convential battles in space or under water.

I'm having a hard time trying to find a scientific explanation for something like a planet made entirely of water. Water on earth did come from asteroids, but every one of those had at least a part of its mass as something other than h2o. The same could be said for a water planet, unless for some reason it was created as a planet of water. By aliens or archeotech or some such. That could be a story element.

The idea is really cool though. I really like the idea of water super compressed to a solid too, even if it is above freezing temperature.

very tasty idears, Aluminium (sic).... ...do please keep 'em comin'! Ice IX super weapon...bloody priceless! Found at the lowest depths of a watery deathworld....oh those poor players....

DJSunhammer said:

Point the first, this is 40k. I am more than happy to sign off on planets made entirely from crystallized hate. :-)

Point the second, I get the vague impression that such planets would form in the outer system and migrate inwards to the habitable zone.

http://en.wikipedia.org/wiki/Gliese_1214_b

+++++If Gliese 1214 b is assumed to be an ocean planet,[4] i.e. the interior is assumed to be composed primarily of a water core surrounded by more water, proportions of the total mass consistent with the mass and radius are ~25% rock and ~75% water, covered by a thick envelope of gases such as hydrogen and helium (~0.05%).[1][5] Water planets could result from inward planetary migration and originate as protoplanets that formed from volatile ice-rich material beyond the snow-line but that never attained masses sufficient to accrete large amounts of H/He nebular gas.[2] Because of the varying pressure at depth, models of a water world include "steam, liquid, superfluid, high-pressure ices, and plasma phases" of water.[2] Some of the solid-phase water could be in the form of ice VII.[5]+++++

The original RPG.net comment said that a new scientist article they read speculated that planets consisting of nothing but water and cometary hydrocarbons were possible, but I fear said article may be behind a paywall.

Like I say though, I feel 'some dude on RPG.net said they read an article that said...' is more than enough research for 40k work.

I guess such a world would find it difficult to evolve life, but I can assure you that the mega-leviathans of the endless oceans of Poseidon VIII are more than capable of swallowing even the largest submersible whole.

Or possibly it merely looks like a planet, but is infact merely a shell of ice that has formed around the sleeping form of Great Cthulhu.

AluminiumWolf said:

I like the sound of this.

What environs would you see as possible for a mission on such a world? A floating or submerged Mechanicus research platform? A Rapture-like underwater city? A gigantic Iron Warriors fortress-sub diving down to drill out some of the volatile superweapon-matter?

Kshatriya said:

The floating bastions are home to the archenemy. Very similar to ice burgs in design in that most of their structure is found far underwater, out of range of any orbital bombardment. What is above water is liberally slathered in AA and orbital defenses and has only a few places to land, which are of course even more heavily defended that anything else. The core of each fortress is based around some strange xenos tech that holds the fortress at a certain depth and coordinate. The core itself is a fortress, but someone, Imperial or Chaos [no one remembers who] has built additional fortifications.

Lethal oceans and undersea defenses mean that a sea born assault is out of the question for the greater part of the Imperial army. The Deathwatch has acquired or built a 'one-shot' craft capable of opening a hole in the defenses for the Imperial guard to make a beach head, similar to a Caestus Assault Ram.

No one really knows who built the fortresses [there are several], but their presence on [Planet Whatever III in System Whatever] means that anyone controlling one or more has a strong base of operations to attack the Imperial war front. Potentially even coming in behind the front lines as it expands, given the position of the system.

That is my immediate idea. You could substitute chaos for any enemy really.

For an environment like that, I would try to get away from the terrestrial paradyme (oh, how I wish this Forum had Spellcheck ..) of natives 'building stuff' and try to incorporate more of an Abyss asthetic, with fluid-based tech rather than solid-centric.

Also, just to show what a geek I am: there was an episode of Star Trek: (shudder) Voyager that featured an 'ocean in space' with no solid center. Just a gigantic globe of floating water...

Good idea's here. I love the more sci-fi scenarios. There's a planet in the Calixis sector called Spectoris. I remember because a character in one of our games was a Noble from there, a fish Baron pressumably. http://warhammer40k.wikia.com/wiki/Spectoris . Although it's specifically got a solid earth crust even it's a long way down.

Assuming that where talking about a world that has surface water (rather than a ice crust like Europa) then there migh still be polar ice caps. Perhaps a group of humans built colonies here originally. Perhaps out of a crashed or landed craft, maybe mostly out of ice.

Even without ice caps perhaps they specifically landed a large ship (or multiples there of) to act as mining vessal with all the space specific apparatus salvaged later.

Other extreme, maybe it's quite a lot closer to the sun and the equatorial regions actually boils, forever raining back down at the cooler poles (constant rain, heavy clouds and strong winds above the surface here.

Native flora and fauna could be based on floating near the surface of whichever zones are suitable for life (i.e. not ice covered or boiling). Perhaps there's forests of seeweed bushes or even trees, all home to any water based creatures you can think off. There might even be substantial enough vegetation to use it as a building material for boats or dwellings. Maybe they are set to float at a certain depth, especially if the surface is boiling or the atmosphere contains toxic chemicals that don't disolve.

Not sure I believe the Ice 9 hypothesis, but it's good enough for a 40K science and a good ending. Other things that offworlders (there on purpose) could be looking for is rare isotopes or water, or other materials disolved in the water.

There might be tectonic like fissures and geysers in the ice core that periodically spew superheated water and other materials into the water. This could be the target of offworlders or exotic native lifeforms.

Finally which antagonists would be on the planet. Chaos and Renagde forces would be there for the same reason as humans. Perhaps an insane standed colony with an ancient relic onboard. Eldar would be there for the same reasons (near enough), but they would have elegant submergable vehicles and maybe even a deep undersea colony. The Tyranids might have turned up if there is a lot of biomass, they would of course have very specific creatures to harvest it, Tyrano-sharks and squids come to mind, obviously. They might even be Necron tombs under the water (maybe they were dug into the ice when it was solid in the outer solar system before migrating inwards.

Face Eater said:

The amount of pressure needed to force water into a solid at temperatures considered super-heated would be enormous. I'm not even sure if there is even a real life theory for it. I'm not even sure if it's possible actually, though what I know about science [admittedly not a whole lot] says that it is.

Nids use water, so their presence would make sense. I can't remember exactly how they process bio-mass though, I'd have to go back and read the Ultrmarines novel again. What I do remember is something like some of the Hive ships dropping to a very low orbit and literally sucking the oceans up.

A Necron presence would need some jiggling to explain. Not even living metal can survive at extreme pressures.

If you read one of the Blood Angels novels there is a description of tyranid under-sea hunters. The last one I think? Which ever one it is where they hunt down Fabius Bile. IIRC, those aren't for consuming bio-mass, they are just general hunter-killer creatures like you would see in a nid ground horde. Something like a carnifex adapted to the sea.

These are cool ideas for anyone that wants to use them, but you would need to be sure to mix ideas that actually make sense [if only a little bit.]

DJSunhammer said:

I like your idea of who would be likely suspects to show up on the planet. Referring to this site warhammer wikia , states on day 51 after the planet's defenses has been destroyed, the ripper swarms clear out the biomass and deposit them into reclamation pools. Capilary towers from the brood ship sends the nutrients into hive fleet. The ripper swarms then board the hive ships and the fleet departs to consume another planet.

So pressumably some kind of piranha like ripper addaption. Not sure if they would be able to have capiliary towers on the ocean bed or just some floating version. But that might not be that important to the players.

Apparently it's not really ice but in a supercritical state.

Surely I'm not the only one thinking that what this ocean world needs is the Archenemy forces drilling down to mine the superweapon matter then, as the good guys rock up to fight them off, they find the place either ominously silent OR in a panic, trying to get off world asap. When the group looks into why, they discover continent sizes, super ice creatures breaking off from the core and seeking to destroy/devour/crystallise those impudent flesh things that have dared to wake them.

@Face Eater
Its likely that the Kraken was a evolution of the Tyranid forces. There were lictors that could swim in the fourth novel of the Blood Angels written by James Swallow. So why not piranha ripper swarms? Makes them more of a force to be reckoned with.

@Professor_Kylan
Your reply triggered an idea. It maybe likely that the super weapon is actually a weapon of Xenos origin, linked directly to the heart of the planet.

Likely that the weapon is some sort of control/ regulator for the gravitational fields of the water planet in some manner/ vapourize water sources..

The archenemy would likely wish to extract it and find a way to use it as their new WMD (Weapon of Mass Destruction). To extract the weapon would mean to destroying the planet.

The archenemy may have already placed cults to infiltrate and study the weapon and an alternative power source so that once extracted, they may continue to power and use it.

The arch enemy would possibly deploy the weapon at a low enough orbit to hit a loyalist planet with it. Throw in the stealth ship technology used by the archenemy in "The Emperor Protects", you have a deadly threat to the Imperium".

...and just like that we have a galaxy-spanning campaign!

Hey guys,

Love the ideas put out here, I've been thinking a long time on how to make an ocean world work!

My thoughts were leaning towards it being kind of like an Agri-World, where its main export to nearby planets (hive worlds in particular), is clean water. I was thinking of maybe a big manufactured ring around the planet that recycled/picked up mass amounts of water to send to hive worlds which have excessively polluted their own by now.

I think this would give any mission to stop the renegades, chaos, or xenos x some more urgency and a reason not to just rip the core out itself. Yes the ice ray it could make would be nice, but then all of the surrounding planets would be sunk with no pallitable water to use. I'm not certain that this would be reason enough for the empire not to use it; a shiney new weapon may be worth sending a few planets to their doom, but at the very least it makes it a second reason not to let the bad guys get it.

Hope that helps some! The big ring built around the planet is mainly so someone can be thrown off and into the water; but I'm sure it would serve some function as well.