If you make it to the end of the Great Ocean Road I definitely recommend driving into Warrnambool and treating yourself at Deep Blue Hot Springs.
We spent 2 hours bathing in 15 different open-air rock pools, sensory caves and cleansing waterfalls (I was obsessed, you know how much I love waterfalls)! We visited on a hot day but the many caves sheltered us from the sun and the cold plunge was used to cool us down when needed (it was still icy cold). They have 2 hour daytime sessions and 3 hour twilight sessions at night (Friday to Sunday - adults only).