When I signed up for Biketours.com’s guided eight-day “The Emerald Tour of Slovenia’s Gems” bike tour, I was expecting sprawling landscapes and quaint villages. What I wasn’t expecting was to be surprised each day by some unique attraction. Postjana caves, Predjama Castle, Škocjan Caves, the most magnificent parts of the trip prove not to be above ground, but underground, as we experience what Slovenia’s karst (limestone) geology really means.