The Blowholes are crevasses in the granite stretching down to sea level far below. With each wave the 'holes' blow air and water up the channel and out the top creating a burst of spray and a loud droning whoosh! See the video below.
The carpark is quite a distance from the Blowholes. To reach them you need to walk a few hundred metres to the top of a long flight of stairs. From there walk along a paved pathway to the rocks. Stroll across the rocks and look towards the ocean and you will certainly here and see the blowholes at work. There is a sign at the beginning of the walk for you to tell whether the blowholes are 'blowing' on the day you visit.
Only a short drive on from The Gap and Natural Bridge, it's a very pleasant walk with amazing views of Bald Head (above) and the Great Southern Ocean (below).
The video (left) shows the blowholes themselves on a calm day in winter (2008). As you can see it is on the sloping side of the rock face as it leans into the Great Southern Ocean. (Be Careful!)
<< On this day they could be heard blowing from the carpark.