Where is it possible to have a fresh water dive between two tectonic plates?

Question

Two tectonic plates and small corners of two others lie under the African continent. These are the African Plate, part of the Eurasian and the Arabian Plates and which other?

Answer 1

Silfra Fissure, Thingvellir National Park, Iceland
The Fissure lies between the Eurasian and the North American continental plates. The plates drift apart at a rate of about 2cm p.a. The water in the fissure is glacier water from the nearby Langjökull and is filtered through porous underground lava for 30-100 years on its path to the fissure. The national park in which the fissure sits has been declared a UNESCO World Heritage site. The other options in this question are all spectacular fresh water dives, but not between tectonic plates.