Stricktly speaking, the Sun only remains above the horizon in summer nights north of the Arctic Circle (66º N), for some weeks, until the Pole - for some months.
Nordkapp, Norway, 71º N - the most visited.
But sun-enlightened nights can be enjoyed since about 60º N latitude for a short period - the well-known Simmer Dim, visible in the Orkney, Shetland and Faröe islands, or anywhere by that latitude.
Fishing through the dimmed night, Orkney islands, 59º N.
In June, for example, the sun is above the horizon for over 18 hours, rising at 4 a.m. But it is still twilight for much of the night, as the sun only dips just below the horizon.
This period of not-quite darkness is known as the ‘simmer dim’, and some can't get asleep.
Dimmed twilight in the Shetlands by the end of June- a large festival usually takes place to celebrate those sleepless nights.
Kulusuk, Greeland, 65º N.
Deep night, Jan Mayen, 71º N.
Ny Ålesund, Svalbard islands, 79º N.
Lofoten, Norway, 67-68º N.
Longyearbyen, Svalbard, one of the most appreciated by cruise ship travellers, 78ºN.
And to help through the night...