All foreign visitors require a valid passport, a 30 day tourist visa and proof of hotel booking or local sponsor in order to enter Nauru. Your visa must be obtained from your local Nauruan embassy before departure. There have been rumours on the Internet that you can get in for up to three days without getting a visa, but that is not accurate.
Nauru's national carrier Nauru Airlines flies to Nauru International Airport from Brisbane Australia, Tarawa Kiribati, Kosrae Micronesia, Majuro Marshall Islands, Nadi Fiji and Pohnpei Micronesia. Schedules change throughout the year; further details are available from the Our Airline website.