There are a few things lurking in the underbrush and swamps of this land that you may not want to runaccrost unawares.
This unassuming brown lump that is at the waterline here is the nose of a snapping turtle. Snapping turtles run from small pencil breakers up to this one which measured about 3.5 feet accrost. If you were to step into its hunting ground, you may not have a foot afterwards. They can look like rocks, or in murky water, nothing at all.
There are much more peaceful cousins of the snapping turtle out there, such as this massive Galapigos Island Tortise. It weighs over 150 pounds and is said to be over 60 years old. They are vegitarians, which makes sence since grasses and veggies are the only things that would not be able to run away from them...
Then there are things that just are uncertain whether or not they are dangerous or not. The Brown Skink here is one of them. Many verieties are poisonus, but some are not. It is best to keep away from things that hide under rocks in most cases.
OOps! What about things that hide in trees, too? This green tree snake (aptly named) isn't something you would want to have drop in for dinner, but it would be more scared of you than you of it. Most tree snakes have sharp teeth which will hurt if they bite, but most are not venomus.
I suggest that before you go camping or hiking in an unfamilliar area, ask around to see what dangers there might be lurking in the shadows. Outfitters, park or ranger stations and local hunting clubs are all good places to check.