Mucking in the Mud

Gettin' dirty just to know the answer...

This is a common subtrope of Geo Effects, where boggy or swampy areas drastically impede your movement. So long as you remain in here, you'll move at a snail's pace, vulnerable to passing enemies. Your jumping, if applicable, may or may not be affected by this, and in fact you may be able to move quickly by repeatedly jumping in and out of the bog.

In some cases the bog may actually be hazardous to your health, dealing damage over time, acting like quicksand and swallowing you whole if you spend too long within, or applying some unpleasant Standard Status Effects.

For some reason, you're never able to simply walk around the hazardous terrain, as the area is almost uniformly flooded like this. Any safer paths will almost certainly be blocked off with fallen logs, impassible treelines, and so on. However, some mudpit look hazardous, but are actually safe enough to cross...

Not to be confused with Bubblegloop Swamp or Quicksand Sucks.

See also Swamps Are Evil and Grimy Water.

Examples of Mucking in the Mud include:

Anime and Manga

A very small bit of this was seemingly featured in the Episode "Training Daze" in Pokémon Chronicles...

Board Games

Candy Land has the Molasses Swamp, which causes anyone who lands on it to lose a turn.

Literature

In The Hound of the Baskervilles, the moor has the Grimpen Mire, which only Jack Stapleton knew how to cross safely. Another character who'd tried to traverse it was sucked down into its depths.
Older Than Steam: The Slough of Despond from Pilgrims Progress trapped unwary travelers unless Help came along.

Video Games

The Nintendo DS game Summon Night: Twin Age consists of around 60% different types of sinky stuff by volume, such as "Poison Marshes" and "Desert Quicksand".
In the PC game Princess Maker 2, there's an "adventure" event which has a few swamps where you can slog around. They're not really dangerous; they have hidden secret shortcuts in them, even.
The "Great Marsh" in Pokémon Diamond and Pearl. The player character is greatly slowed down when he/she runs through it, and, in some places, he/she can even get stuck.
Valkyrie Profile: Lenneth has 2 places known, with mud, they are Nethov swamp and Salerno Academy, you can only find them on normal and hard mode.
Super Mario Strikers Charged has a stage known as The Dump which is muddy.
One of the special minigames had this feature in Mario Party 7.
Castor Wilds in The Legend of Zelda the Minish Cap consists of a quicksand-like marsh with safe zones in the form of raised land. Traversing it safely requires getting ahold of the Pegasus Shoes, which let you dash across before the muck can take hold.
"Grail Mountain" with its purple puddles and "East Ghoss Forest" with its mud in Grandia 2...
One area in Zelda II the Adventure of Link is a thick marsh. You'll move more slowly both on the overworld and in battle sequences, though your enemies are, of course, completely unaffected.
Metal Gear Solid 3: Snake Eater has pools of mud like this. If the mud is deep enough, Snake will eventually sink to his death. What's more, the mud houses leeches which will cling to Snake and sap his stamina.
One Piece: Unlimited Cruise: Episode 2 had "Boggy Isle" with this feature...
Lufia: Ruins Of Lore had Jungle Spire which have mud spots that take you down to a cave area if you step in the right areas...
The swamp level in Turok 2 has regular mud that slows you down, and quicksand that instantly sucks you down.
Although it's technically more of a swamp, both Demon's Souls and Dark Souls feature this, complete with reduced mobility and absence of rolling. In both games, the swamp is also poisonous, so staying in it for long isn't exactly advisable. In the first game, swamp jellyfishes that live in it can be killed to provide anti-poison herbs, but the absence of rolling is lethal since any other enemies can cross the swamp with nary a hitch, unlike you. In the second game, the enemies that live on it can still charge at you at maximum speed, but an equippable ring exists so that movement penalties are removed entirely when walking on swamps. Oh, and fast rolling (<25% equip burden, or Dark Wood Grain Ring ninja flip) is not disabled in the swamp.
Some of the jungle levels and one south pacific level in Tomb Raider III have mud that makes Lara sink if she steps in it. In some spots, the mud is deep enough to make Lara be completely submerged and she will quickly drown.

Web Games

In Gretel and Hansel 2, Gretel can wade around the swamp but can't get across completely without her brother's help because of a snake that lurks halfway across.

Western Animation

Adventures from the Book of Virtues
- In the episode "Self-Discipline," Annie and Zach were walking on mud while they enter Plato's Peak.
- In one scene of the episode "Moderation", Socrates is seen stepping in a puddle of mud, much to Aristotle's annoyance.