The Great Ocean Road has some of the best beaches in the world, but when the surf is flat or choppy, here are my top two picks for freshwater alternatives in the region:
1. Marriners Falls is a quaint ferny grotto that offers a cold shower in crystal clear water plus a small playing area for floating or splashing around in at the base of the falls. Direct sunlight only reaches into the alcove around the middle of the day, which is the best time to visit. To get there follow the sometimes confusing signs from Apollo Bay to the Marriners Falls car park. From there it's a 1.7 km walk with 8 very shallow river crossings that helps to keep this place a secret from most tourists. Maps are available from the visitors centre in Apollo Bay.
2. Parker Hill is a seaside camping spot in the Otway National Park that has a cascading creek which flows into a sizeable swimming hole as it reaches the coast. To go for a swim, walk down the very steep marked track to the bottom of the hill and then turn left. The pool is partly tidal, but because fresh water is less dense than salt water, you will generally be swimming in the fresh water on top layer of the pool. From the Great Ocean Road, take the road to the Cape Otway lighthouse and turn off at the signs to Parker Hill. Either walk the last 2 km to Parker Hill or drive (dry weather only) on the sand track, remembering to shut the gates behind you.