If you're looking for a challenge to conquer on your ATV, look towards Australia, specifically the Victorian High Country area.
The Victorian High Country has an abundance of wildlife you are likely to meet when you're riding your ATV. Snakes and large insects especially, the flies are particularly attracted to bright colors and many species bite. A favorite stop for most ATVers is Big River which is a popular area for camping.
Frenchmans Spur Track is an easy climb for most ATVers as it is a well used and well graded track. You will be rewarded with a beautiful over the Big River valley as it stretches out to the North.
Shortly thereafter there is an ATV trail that leads off from a helipad and has a large amount of scratchy over growth. If you're not wearing heavy long sleeves, you might be sorry you took this ATV route.
There is water in the area, so be sure you know how to ford it correctly or you are liable to get stuck. There are no bog holes in the area so you don't have to worry about encountering a lot of mud on your ATV. If you follow the ATV trail in the area of the Springs, you will come upon a major dirt road, follow this road and you will find a small waterfall.
Next you will encounter McAdams Gap where you will need to climb your ATV over an short embankment and then turn off at the Goulburn State Forest sign. This rocky, graded track leads up to Mt Matlock Fire Tower. This is one of the tallest towers around at around 50 meters. The current metal tower replaced the shorter wooden one a couple of years ago.
If you wish to spend the night on these ATV trails, Comet Flats has a camping area and there's nothing like sleeping under the stars after a great day of ATVing.