Sprawling over forty-five hundred square miles, San Diego is the second most populous county in California, and fifth largest in the United States. Boasting seventy miles of coastline and one of the most moderate climates in the world, it's no wonder more than three million residents have settled into this corner of the nation. Whether you like to surf the ocean waves, cruise the coastal highways, hike through arid canyons, snowboard in the mountains, or enjoy a cool desert evening, everything is within a day's drive. First discovered by Spanish explorers in 1542, the region waited over three hundred years to become an official state. Today, it's home to a large military presence, including major bases for the US Navy, US Marine Corps, and US Coast Guard. It's also a magnet for cutting-edge technology and science, including some of the most renowned educational institutions in California. The temperate climate is also a major contributor to the top-tier agriculture and tourism industries. So whether you're a Southern California native or just dreaming you are, 100 Things to Do in San Diego Before You Die is packed with obvious and not-so-obvious opportunities to discover the best that San Diego has to offer.