In April 1815, the most powerful volcanic blast in recorded history shook the planet in a catastrophe so vast that 200 years later, investigators are still struggling to grasp its repercussions. It played a role, they now understand, in icy weather, agricultural collapse and global pandemics — and even gave rise to celebrated monsters. Around the lush isles of the Dutch East Indies — modern-day Indonesia — the eruption of Mount Tambora killed tens of thousands of people. They were burned alive or killed by flying rocks, or they died later of starvation because the heavy ash smothered crops.