1. Bucharest: Muddy Volcanoes and Salt Mine Private Day Tour
Experience an unusual collection of natural attractions in Romania with this day tour from Bucharest. Begin your trip by journeying deep underground to see the enormous caverns of the Unirea Salt Mine. Slanic Prahova Saline is the largest salt mine in Europe. Now the old mine is currently open to the general public, being used as a leisure place. Underground is also a sanatorium for asthmatic patients who are provided specialized medical care. The ventilation of the mine is natural, with a constant temperature throughout the year of 12 degrees Celsius. Then it’s onto Buzau County to marvel at the fascinating geothermal spouts of mud and gas known as the Berca Mud Volcanoes that are rarely found in Europe. Its most spectacular feature is the mud volcanoes, small volcano-shaped structures typically a few metres high caused by the eruption of mud and natural gases. As the gases erupt from 3000 metres deep towards the surface, through the underground layers of clayand water, they push up underground salty water and mud, so that they overflow through the mouths of the volcanoes, while the gas emerges as bubbles. The mud dries off at the surface, creating a relatively solid conical structure resembling a real volcano. The mud expelled by them is cold, as it comes from inside the Earth's continental crust layers, and not from the mantle.