The midnight sun run has taken place in Laugardalur valley in Reykjavik at Midsummer or summer solstice since 1993.
Upcoming races are:
2018 Suzuki Midnight Sun Run - Thursday evening June 21st
2019 Suzuki Midnight Sun Run - Thursday evening June 20th
Registration for the 2018 race will start on Friday, January 12th, 2018. Information about entry fee, program, etc. will be available here at marathon.is in the beginning of January 2018.