Silfra is a rift formed in the Mid-Atlantic Ridge – the divergent tectonic boundary between the North American and Eurasian plates – and is located in the Þingvallavatn Lake in the Þingvellir National Park in Iceland.
Wikipedia https://en.wikipedia.org/wiki/Silfra
Address Iceland
Coordinates 64°15'18.685" N -21°7'0.989" E