Time Out says
The Mermaid Pools are on crown land, which means you won’t find any of the facilities you’d expect in a National Park, including clear signage. The trail to get to this site is signalled by small blue and yellow markers attached to trees, and it’s relatively easy to get lost, so make sure you bring a friend, and provisions. This spot is where the first recorded European sighting of a koala took place, so keep your eyes peeled for the sleepy marsupials. There are two walking tracks that will get you to the pools, one high and one low. The walk to get to the pools is about five kilometres, and the track is not looped. Once you arrive, you’ll see a stunning green basin, wrapped by cliffs, with the Bargo River flowing into it from above. The site is a sacred space for local Aboriginal community, the Tharawal people.
It does get hot in the west, so if you do feel like swimming, Stirling suggests heading to the carpark on the corner of Rockford Road and Charlie’s Point Road. There, the river gets wide and deep, and a great swimming spot is easily visible and accessible straight from the road. The river is downstream from a coal mine, so Stirling suggests you don’t drink the water, and only swimming “ after there's been a flush of rain.” “People always need to take caution when swimming in rivers… Have a swim, but take it easy, you know?”