Which Oceanian country spans three different time zones?

Kiribati is the Oceanian country that spans three different time zones.

Kiribati consists of island groups scattered across a vast area of the central Pacific: the Gilbert Islands, Phoenix Islands and Line Islands. These groups observe Gilbert Island Time at UTC+12, Phoenix Island Time at UTC+13 and Line Islands Time at UTC+14. Kiribati does not observe daylight saving time.

The country’s unusual time-zone arrangement is closely connected to the International Date Line. Before 1994, the eastern island groups were nearly a day behind the Gilbert Islands despite belonging to the same country. Kiribati shifted the Phoenix and Line Islands forward by a calendar day on 31 December 1994 to simplify administration and communication.

That adjustment made the Line Islands, including Kiritimati, among the first inhabited places to enter a new calendar day. A common mistake is to assume that a country must have three mainland regions to span three zones; in Kiribati, the zones result from the enormous east-west spread of its widely separated Pacific islands.