Iceland sure ain't on anyone's list of top snorkeling destinations, but here's a unique experience which just might intrigue you (with a lot of insulation, of course, since the water's around 2C⁰/36⁰F), snorkeling/diving between the continental plates of Europe and North America: https://www.globeguide.ca/silfra-fissure-iceland/


(Carsten ten Brink)