From 1831-1836, Charles Darwin circumnavigated the globe aboard the HMS Beagle. In the Galapagos Islands and elsewhere, Darwin collected data that, after decades of study and reflection, formed part of the basis for his publication On the Origin of Species. The ideas presented in that volume remain the foundation of all modern biological thought. We will address the historical and cultural context of Darwin's era, follow the five-year journey, discuss how Darwin came to his ideas, and explain his theories in detail.