The Antarctica section is supposedly only visible to those who are logged in as a user with specific permission granted to see it - members of the 2014 expedition.
That means that if you are not logged in, it will be invisible - or similarly, if you are logged in as a user without those permissions.
Thanks Chris. I am a member - going to Antarctica and have 'registered' on the website to participate on the Antarctica forum. That's why I find it weird that it doesn't come up 100% of the time.