Measuring in at 1,080 square miles, the Toba Caldera is the largest volcanic lake in the world. Sometimes being described as ‘Yellowstone’s Big Sister’. When Toba last erupted an estimated 70,000 years ago, it literally blew its top off. It is the largest know eruption to have happened in the last 25 million years, blanketing the earth with ash and dust that brought on the last know volcanic winter. Decreasing global temperatures by as much as 27 degrees Fahrenheit. There have been recent eruptions at Toba indication it is still a very much alive and active volcano.