After stealthily traveling thousands of miles across the ocean, swells slowly rise from the deep as they glide toward shore. Whether they rear up and crash against jagged cliffs or lap quietly toward grass-covered dunes, they are met by people in ever-increasing numbers. A large and growing number of people live, work, or play near the shoreline. Coastal morphologies and the processes that continually remake them increasingly affect coastal economies as well as sightseers, and vice versa. These interactions are prompting increased study of the Earth's diverse coastal environments.