History Main / NoFlowPortal

* ''{{Stargate SG-1}}'' and ''StargateAtlantis'', over and over again. Having one end of a Stargate immersed in water doesn't result in it flooding the other end (or having said water disintegrated if it's the destination end), nor does it suck the air out of the room if the gate is opened into the vacuum of space.

* This is generally played straight for portals in DungeonsAndDragons[[hottip:*:AWizardDidIt, often literally]], though ForgottenRealms plays with it by featuring portals that ''only'' lets the atmospheric conditions/water, etc through, and blocks creatures and constructs from going through. Don't want air elementals to disturb that fresh air you're bringing in from the Elemental Plane of Air, after all.

* Averted in DavidWeber and Linda Evans ''Literature/HellsGate'' series if only in passing. At least one portal connects two points that are very disparate in terms of altitude and while the situation stabilises eventually you can still see where the initial gale scoured part of the area down to the bedrock and circumstances still conspire to produce rather impressive winds under certain conditions.

* Averted in {{David Weber}} and Linda Evans [[HellsGate Hell's Gate]] series if only in passing. At least one portal connects two points that are very disparate in terms of altitude and while the situation stabilises eventually you can still see where the initial gale scoured part of the area down to the bedrock and circumstances still conspire to produce rather impressive winds under certain conditions.

* In CrashBandicoot3Warped, Crash can take a Time Twister portal from the WarpZone straight to the underwater levels and no water escapes from there to the present.

* In TransformersPrime the Autobots space bridge can open into space without sucking the air from the base into a vacuum.

* In ''{{Spin}}'', the enormous portal connecting the Indian Ocean to a distant alien planet not only doesn't let water pass through, it doesn't let ''anything'' pass through unless it contains sentient passengers. A manned boat will pass through; the same boat floating by itself won't. Justified in that the portal is to some extent, a sentient, or at least reasoning entity, and can thus decide what goes through and what doesn't.

* In {{Spin}}, the enormous portal connecting the Indian Ocean to a distant alien planet not only doesn't let water pass through, it doesn't let ''anything'' pass through unless it contains sentient passengers. A manned boat will pass through; the same boat floating by itself won't. Justified in that the portal is to some extent, a sentient, or at least reasoning entity, and can thus decide what goes through and what doesn't.

* One episode of {{Angel}} had the titular character black-mailed into entering a Hell Dimension to save someone. He gears up before entering only for all the weapons to drop to the floor when he vanishes.

* Averted in [[{{Portal2}} Portal 2]], as [[spoiler: a portal on the moon causes Wheatley, the space core, and various junk to be sucked out into space.]]

Portals are sometimes helpful. Sometimes they're [[PortalSplat unreliable]], or [[TeleFrag dangerous]]. Sometimes, though, they're just weirdly selective.

* Averted in Portal2, as [[spoiler: a portal on the moon causes Wheatley, the space core, and various junk to be sucked out into space.]]

* Averted in Portal2, as [[spoiler: a portal on the moon causes Wheatley, the space core, and various junk to be sucked out into space.

NoFlowPortal is a strange effect where a portal immersed in whatever medium - a fluid, like a body of water, or a strange kind of atmosphere - or exposed to conditions which would otherwise affect either side of the portal, [[PhysicsGoof for some]] [[ArtMajorPhysics reason]] doesn't let it through even when the portal is working. TheHero can swim into the portal on one side and walk out of it the other side, yet the body of water he swam in remains as stolidly fixed as if it were up against glass. The hero could even cause an explosion next to a portal, and the people on the other side won't even feel a breeze.

For those of us who like to dwell on this sort of thing, it often leads to a FridgeLogic moment when you wonder why biological matter (which itself contains a lot of fluids, including water) can pass through but a body of water can't. MSKT3Mantra is usually enough to dismiss it.

* In the first series of {{Primeval}}, averted: a portal which opened in the Cretaceous sea allowed water to flow into the present and flood a basement, resulting in the Hesperornis getting through.

* In [[SpyroTheDragon Spyro 2]], the portal from Aquaria Towers to Summer Forest is underwater and yet the GibliHills aren't flooded at all.
** In [[SpyroTheDragon Spyro 3]], a portal to a chinese fireworks factory, an abandoned ghost ship and a SlippySlideyIceWorld are all accessed only by underwater lake, yet the lake hasn't emptied its water through it at all.
* In CrashBandicoot3Warped, Crash can take a Time Twister portal from the WarpZone straight to the underwater levels and no water escapes in-between.

A strange effect where a portal immersed in a fluid, like a body of water or a strange kind of atmosphere, doesn't let it through even when the portal is working. TheHero can swim into the portal on one side and walk out of it the other side, yet the body of water he swam in remains as stolidly fixed as if it were up against glass.

The opposite of this trope, naturally, would be where fluids do flow through the portal, like a strong gust which is sucked in. This is quite common in fantasy works where the portal in question leads to somewhere nefarious and supernatural, though it'll always be less about thermal currents and fluid dynamics and more about [[RuleOfPerception looking impressive]] - how else to make a portal look foreboding and scary?

A strange effect where a portal immersed in a fluid, like a body of water or a strange kind of atmosphere, doesn't let it through even when the portal's working. TheHero can swim into the portal on one side and walk out of it the other side, yet the body of water he swam in remains as stolidly fixed as if it were up against glass.

This trope isn't restricted to water, though water is one of the easiest things to fall afoul of it. Different atmospheric conditions can be strangely shy about crossing the portal barrier. This is obvious enough with two completely different atmospheres, but for a few [[ViewersAreGeniuses more observant viewers]], this trope may manifest itself in a case where the atmospheres are the same but one is blowing over the portal on one side and having no effect on the other side. What you'd expect to happen is that the air would get sucked through the portal as the wind creates an area of lower pressure in the other world. Even ''sand'' may fall victim to this trope - SandIsWater, for a given definition of 'water' - though it is usually just partly submerged in the sand rather than completely smothered by it.

The opposite of this trope, naturally, would be where a strong gust flows through the air and into the portal. This is quite common in fantasy works where the portal in question leads to somewhere nefarious and supernatural, though it'll always be less about thermal currents and fluid dynamics and more about [[RuleOfPerception looking impressive]] - how else to make a portal look foreboding?

For those of us who like to dwell on this sort of thing, it often leads to a FridgeLogic moment when you wonder why biological matter (which itself contains a lot of fluids, including water) can pass through but a body of water can't. MSK3Mantra is usually enough to dismiss it.