The Diomede Islands are 2.4 mi, an international border, and 21 hours apart.
These islands are located in the middle of the Bering Strait. The western Ratmanov Island belongs to Russia and the eastern Krusenstern Island belongs to the USA. The islands are separated by an international border and the International Date Line. So, when it’s Saturday at 6 AM on the American island, it’s Sunday at 9 AM on the Russian island.