The walk to 40 foot falls begins at the back of lake Alexandra in Mittagong, You will see a sign posted directing you to the start of the track.
The only part that is unmarked on the track and not long into the walk is at the second bridge to you come (pictured below), turn left at this intersection. This will lead you to a fire trial. The rest of the walk is marked by red tabs or poles with a red tip spray painted on them. The first example you will see of this as walking from the firetrail, there is a red post indicating for you to follow the footpath just off the fire trail to your right.
The tack is mostly easy but involves steep stars, a long flight of steps and creek crossing. The track takes you through lush fern forest and mostly follows the creek.
When you get to the falls, you may either follow the rough path down the the bottom of the falls, there is no straight forward way do to under the waterfall so you will have to work your way down the rocks. However getting under the waterfall is a picturesque part of the walk, you can get directly under the waterfall or explore the cavern under the waterfall if you don't want to get wet. The other path for the waterfall takes you up some steps and then to a ladder that will take you to the top of the waterfall.
While there is no clear or defined swimming hole, there are plenty of deep pools coming up the the 40 foot falls that you may hop into to cool down should you chose to do this walk on a hot day.