The inclusion of engineering in the Next Generation Science Standards (NGSS) as a key component of K-12 science learning has provided both opportunities and challenges for elementary teachers. One challenge is integrating the design thinking processes that undergird engineering with core science concepts and current issues facing scientists and the broader world (NRC 2007). The study of oceans, waves, and shorelines allows children to explore factors that impact both humans and the environment and provides a context for authentic engineering challenges that are accessible to elementary students. The engineering challenges the authors present here were integrated into a larger unit on living shorelines. The ideas were originally developed as part of a teacher professional development institute in which K-5 teachers explored the local shorelines of the San Francisco Bay Area and engaged in engineering challenges to better understand the role of engineering in the NGSS. The engineering challenges were then piloted with children at a science camp for grade 3-7 students and then taught as part of the science curriculum in a fourth-grade classroom. In each of these settings, the driving question was: How do we engage with the coastline in ways that benefit nature and humankind through engineering design?