In theory yes, but there is a whole lot of empty ocean in all directions but the north (New Zealand nonwithstanding), and that happens to be an intensely monitored region of the globe due to Australia's desire to prevent refugee arrivals by boat. "Stop the boats" is Australia's "build the wall".

Whether the border force will put any effort into apprehending a boat that's leaving, rather than entering, I can't say, however it's hard to slip under the radar (or sonar, as the case may be).

https://osb.homeaffairs.gov.au/