The 7th Gate: Quicksand Marsh
In this wet, mud filled environment, there were serious problems for the shinobi/kunoichi whom were unlucky to come this way. For in this edge of the forest, there held many natural calamities. There were exotic plants, some that resembled Venus Flytraps, but with a sick twist. They expelled various gases that led to numerous impacts on the person, such as Passing out, and ranging from small to large degrees of bodily poisoning.
Also, mere trees were more than that. If a person were to even touch it, they would be enchanted by a strong illusion, one that confused them into moving in circles. Also, most of the ground contained quick sand, ones that could suck the victims in the ground like ants from an anteater.
In the skies, it is much more brutal. There are extremely large insects in the skies, including Bees, Wasps, and Mosquitoes. Even one strike can be fatal towards the strongest of participants. However, beware the Bees, and Wasps, their venom in large amounts being extremely lethal. It is not something to deal lightly with.
In the grounds below, there are stalking predators. There are several lions, and tigers scattered across the landscape. They often attack in numbers, it increasing their chance of success. Although, they aren't powerful enough to kill due to the lack of Jutsu, they prefer attacking people when they're down. They're smart like that.