Deep in the Jungle of Doom is the 11th book in the Give Yourself Goosebumps series.
Plot[]
You are on a class trip out in the middle of the Amazon Rainforest. You and your friend Zoe abandon the group and encounter a gargoyle that chases you and her through the jungle. The two major storylines of the book branch from the decision to either run into a clearing or towards a pool. By running into the clearing, you eat a fruit and turn into a fish monster. If you jump into the pool, you and Zoe end up encountering cave creatures.