Every swamp has a 50% chance of being a green swamp. This is a new type of swamp with new characteristics.
Green swamps have the grass and foliage color of a jungle biome. Green swamps are also denser and have taller trees; the trees are three times as tall as normal swamp oak trees, and there are twice as many trees per chunk.
The green swamps also have fallen swamp trees in the water, which break up the monotony of the swamps.
Just as it occasionally rains, fog now sometimes appears in all swamps, mainly affecting green swamps. This fog allows undead monsters to spawn even during the day and makes it significantly harder to see.