If you don’t have a local contact, or don’t know where you’ll be staying, you can list the locations you plan to visit while in Australia and activities you have planned out.

If you’re applying for a tourist visa, and you know where to stay but haven’t made the booking yet, you can still refer to the location in your application. If you’re a student, use the address of your Australian educational institution. If you are applying for a crew member visa, you may provide the name and address of the airport or port where you will make your transit.

Even if you only need to transit through the U.S. airport, you still need to apply for and obtain the C1 visa (or an ESTA, if you qualify for one). Additionally, you must present proof of intended departure from the U.S. within no more than 29 days.