All foreign visitors must have a valid passport to enter Australia.

All visitors except holders of Australian and New Zealand passports require either a visa or an Electronic Travel Authority (ETA) before entering Australia. (New Zealand citizens are issued with a visa on arrival in Australia.)

For more information visit the official web site here

The Australian Government website provides links to authoritative sources for information on a range of other matters of use to you.  For example claiming a refund on goods and services tax that you pay while in Australia, contact information for Embassies and Consulates if you should need assistance from your home government while in Australia, bringing medicines into Australia, quarantine restrictions and more.

 In Australia, around the Riverland area in South Australia and the Sunraysia region in North-Western Victoria, you are not allowed to bring fruit, vegetables or some plant material into the region, in order to keep fruit fly out of these produce rich areas. When crossing the border from Victoria to South Australia (into the Riverland region) there is a 24hr manned fruit-fly checking station. If you do not forfeit any fruit, and fruit is found, you will be fined.

If you're travelling north of Cairns along the Peninsular Developmental Road there are Quarentine Checks to ensure you're not carrying any prohibited goods such as fruit and vegetables.

There are more strict quarantine restrictions for Tasmania here