When you get down to the detail you discover that applicants must have "At least one year's relevant experience", and short-listed candidates will be subjected to identification verification, health checks, police checks, visa eligibility, psychometric assessment and assessment of written English.
In addition, the final selection process will involve team challenges, physical, skill based and aptitude tests. Writing skills will be important, as the person selected will have to write a blog, and also prepare a video diary.
It's a great job, but the thousands (or tens of thousands) who apply will rapidly be whittled down - most of them won't meet the criteria.
I haven't been to Hamilton island, but I've flown over it, and I think that six months there would be five months too many - not that I would stand a chance of qualifying anyway, I don't have any scuba-diving experience, and I couldn't water-ski to save my life. I would probably fail the psychometric assessment as well.