@skribe @michcampbell @ajsadauskas It's fully integrated into Sydney's Opal public transport ticketing system.
For a full-dare adult, fares are capped at:
$50 a week
$18.70 a day (Mondays to Thursdays),
$9.35 on Fridays, Saturdays, Sundays and public holidays
In other words, if you go on a Friday or a weekend, it's $9.35 from Circular Quay all the way to Parramatta and back by ferry.
And as an added bonus, almost any other train, tram, metro, or bus trips that day will be free as well.