Holland Americza uses the Stiletto Entertainment talent agency to book its entertainment for cruises. You will need to look up when they are having auditions, times and areas vary.
To apply for a job as a singer, go to their website for entertainment positions at Holland America. You'll find all of the job requirements and an application form that you can submit.
Well, one way to do this could be to google their company and then try to find a contact number or email on their website, and ask through email or phone.
