Enfolded behind their own wall of verdant hills and ridges, the waters of Lake Toba now fill what is perhaps the largest volcanic caldera known to man. In fact, it's accepted that the 100-kilometer-wide cone here was responsible for one colossal climate-changing event more than 77,000 years ago, which spewed magma and ash into the atmosphere and caused a volcanic winter across the globe. Those seismic days are all but gone, and today Lake Toba tour guides instead welcome visitors to a high-perched paradise right in the middle of the Sumatran mountains. It's a place where lopsided longhouses offer rural stays between packs of swaying palm trees, misty rainforests drop straight into the lake, and Batak canoes flit across the surface. To have an initiation in the local Batak culture that dominates these Indonesian highlands, head to earthy Samosir for a visit the local houses of Tomok village or the ancient stone courtyard at Ambarita, before bathing in the nearby waterfall or hiking up the volcano.