Swamp

Swamps are mild, murky biomes. There are two variants in the biome family.

Description
Swamps are low-lying, damp biomes. The elevation often lowers enough to go under sea level, resulting in large patches of swamps being flooded. Water in swamps takes on a gray color on the surface, turning pale yellow when the player is submerged in it. Lily pads frequently generate on the water's surface, and seagrass covers the bottom of flooded areas. Patches of clay often form on the bottom of flooded areas, replacing the dirt floor. Trees that grow in swamps are covered in vines like the trees in jungle biomes. Exposed grass and leaves in swamps vary in color, as swamps themselves have temperatures vary randomly, resulting in different shades of green for different patches of the swamp; typically however, the color is a very dark, dull green. Despite the varying temperatures, it only ever rains in swamps.

Sugar cane grows frequently in swamps, and huge mushrooms may grow as well. Blue orchids also grow exclusively in swamps. Occasionally, a swamp hut may generate within the normal swamp variant. Swamps are the only biome aside from deserts where fossils can be found; they may rarely (in 1 out of every 64 chunks) generate underground. Slimes spawn naturally in the default swamp variant.

Survival in swamps can be somewhat easy if the player finds a large-enough clearing for a shelter. Wood supply is good without being overwhelming, water is abundant (though perhaps unpleasantly colored), and terrain is often flat. Witch huts can also be converted into witch farms, should the player want to easily harvest their drops. However, slimes spawning alongside hostile mobs can make nighttime survival more difficult if the player doesn't light up their surroundings.

Variants
There are a total of two different swamp biome variants.

Swamp
The Swamp biome is the standard swamp variant. Non-flooded areas of this biome feature relatively flat terrain, similarly to plains biomes, though with significantly more trees and less tall grass. Some parts of the swamp may have marsh-like terrain, where the grass has multiple single blocks of water generating within it. At nighttime, depending on the moon phase, slimes may spawn at Y-levels 60-80 alongside other hostile mobs, making swamps the only places outside of slime chunks where slimes can be found. Swamp huts and fossils also generate in this biome.

Swamp Hills
The Swamp Hills variant features hillier terrain rising up between the flat marshes. These hills are generally shorter than the hills in other biomes, though can still tower over the otherwise low-elevation swamp. Additionally, flooded areas in swamp hills tend to reach lower depths than the rest of the swamp, sometimes deep enough to have a gravel floor in place of a dirt floor, like oceans. Swamp huts will not generate in swamp hills, nor will slimes spawn, but fossils may still generate underground. Additionally, seagrass does not generate in flooded areas of swamp hills.

Gallery
Note that images with blue water were taken before 1.13, which changed the color of water in swamps from blue to gray.