In Reykjavik, Iceland from May 19 until July 24 the sun does not set far enough below the horizon for it to be considered night according to Halacha. Therefore the following rulings apply.
1. Maariv may be said from Plag Hamincha, in which case Mincha should be said before Plag Hamincha.
2. Some Halachic authorities maintain that evening Shema may also be said from Plag Hamincha. Others maintain that one must say Shema again after Shkiah. The Alter Rebbe maintains that Shema should be said again after Alot Hashachar (when following the Alter Rebbe's opinion, it is best to say Shema just before Alot Hashachar as well, to be Yotze according to all opinions).
3. Shabbat and Yom Tov candles may be lit (and begin Shabbat and Yom Tov early) from Plag Hamincha until Shkiah (including the first night of Shavuot).
4. On Motzei Shabbos Maariv may be said from Plag Hamincha (including Ata Chonantanu). Havdala may be said from Alot Hashachar. Fire and Besamim should not be used for Havdalah.
5. Kiddush Levana should not be said.
6. Sefiras Ha'omer may be said after Shkiah (with a Bracha).
Reykjavik does not have an Eiruv.
Please contact the rabbi for further questions.