[Christmas Island](http://en.wikipedia.org/wiki/Christmas_Island) is an island of Australia far off the northwest of the mainland, much closer to Indonesia.

![Where is Christmas Island?](https://i.stack.imgur.com/AGMuD.png)  

(Thanks to Wikimedia Commons for the map)

I know I can fly there but [Wikitravel seems to suggest there's no regular ferry or boat transport](http://wikitravel.org/en/Christmas_Island#By_boat).

It does mention that I might be able to get there by private yacht or by cruise ship. Does anybody have some actual information about how to find either of these and how much it might cost?

I'd like to know both about getting there (or back) from Australia and from Indonesia. Would one be easier than the other? Would customs and immigrations rules make the latter too tricky? Would it be a good way to get from Australia to Southeast Asia overland?