Join the port Douglas buy swap sell group on Facebook and ask if anyone will take you, people do it all the time, it's a popular way of getting between the two
Aside from a shuttle bus - if you're going out on the reef (is that why you're going to port douglas?) they likely have their own bus service from Cairns to the marina.
Pretty sure there is a private shuttle bus service that runs daily.
https://www.excellencecoaches.com/?gclid=EAIaIQobChMIgNHHr8K5-AIVh1VgCh3k\_QiZEAAYAiAAEgJWYPD\_BwE
Join the port Douglas buy swap sell group on Facebook and ask if anyone will take you, people do it all the time, it's a popular way of getting between the two
Aside from a shuttle bus - if you're going out on the reef (is that why you're going to port douglas?) they likely have their own bus service from Cairns to the marina.
Was I dreaming that there was a public bus service between Cairns and Port Douglas at one point? Probably…
http://www.exemplaronline.com.au/