SuperSaver: Small Group Silfra Snorkeling and Lava Caving Adventure from Reykjavik. Visit Þingvellir National Park, a UNESCO World Heritage site, for a day of spelunking and snorkeling during this full-day, Eco-adventure from Reykjavik. Accompanied by your certified guide, visit the hidden underworld of a typical Icelandic lava tube for some caving exploration. You'll also see the impressive Silfra fissure, where you will get the chance to snorkel between the tectonic plates of America and Eurasia. Round-trip transportation from pick up points in the downtown Reykjavik area, and all necessary gear are included. Book this Tour and Save 23%! SuperSaver: Small Group Silfra Snorkeling and Lava Caving Adventure from Reykjavik.