The Green Mountain's section of Lamington national park, which everyone calls O'Reilly's, has some incredibly beautiful hikes. You should also give yourself plenty of time to do the 11 km Box Forest Circuit. This is no way a difficult track but so beautiful you will want to linger at many places to admire the scenery.
One of many waterfalls by the Box Forest Circuit Track
Note: The name O'Reilly comes from the O'Reilly family who in the late 19th Century were carving out a dairy farm in the middle of an area that would become Lamington National park. Since then they have turned to providing accommodation to people coming to enjoy a holiday in the Rainforest. Mick O'Reilly become the first National Park Ranger in Australia.
The Box Forest Circuit starts at O'Reilly's Forest Retreat and you first must descend a gently sloping path into the valley. I recommend following the track in an anticlockwise direction as this saves the best waterfalls until the end.
As you follow the creek you will understand why this is such a popular walk. A beautiful pool under a water fall is followed by another, and yet another, and where there are not water falls there are cascades and just the stream in general.
Back at O'Reilly's Mountain Cafe it is time for coffee, cake or a meal at their cafe and enjoy the views. Just a note, most people are a little disappointed with the cafe at O'Reilly's. Generally it is over priced for the quality of the food and service. However you will have to return down Lamington National Park Road to find any other cafes.