Vivid Sydney is a unique annual winter event of light, music, and ideas return to illuminate Sydney from 25 May to 16 June 2018. With the Harbour City transformed into an outdoor lights sculptures exhibition, the best way to experience this amazing light festival is with a Sydney Harbour Cruises.
"Vivid Lights" Cruises are currently available discounted starting from $25 each. These will certainly shoot up when the even starts on 25th.
Rate table at time of posting: https://i.imgur.com/WyPo8A9.png
There are other cruise providers as well e.g. FantaSea if these do not suit your dates/timing but rates will vary. There are also some cheaper options on older boats on Groupon if you prefer that. Alternatively you can of course walk around the exhibits and harbour for free but do expect heavy crowds.
Enjoy!
AMEX Card holders also get free entry to Cruise Bar Rooftop which has free food
https://www.americanexpress.com/au/content/vivid/
I tried posting this as a deal but it's so complicated and got spooked :(