This is an area of the inner Amazon Rainforest in Brazil.
Made in WorldPainter with Lentebriesje's Tree Repository, this is as close as you can get with a realistic rainforest in Minecraft. This massive forest has two mighty rivers: Rio Negro in the North, and Rio SolimÃµes in the South. But, there's many small rivers flowing into the big ones.
Update 2.2 (Diversity Update): More plant species, ground covered in dirt, denser forests and vegetation and harder to get food
Tree leaves may not decay when cut down. Watch out for monsters though, even during the day. This adds realism, because there could be dangerous animals in the real world rainforests.
In multiplayer this map could be used for survival games and factions.
A project to explore the world a great deal, exposing many clearly defined biomes. There are a few glorious deserts as well as one proper plain. Of course, many forests, possibly a few rainforests, but those are really quite indistinguishable from the denser temperate forests. Let's hope there is more eye-candy and rainforest-type canopy in the future to help diversify all the biomes!