National Seashell Day is celebrated on June 21, marking the first day of summer and honoring the charm of seashells. Established by the beach communities of Fort Myers and Sanibel in southwest Florida, the day encourages people to enjoy activities related to seashells, such as visiting beaches, collecting shells, and learning about different types of shells. Typical customs include digging toes into the sand and identifying various seashells, with a focus on educational aspects for both children and adults. The day also highlights the ecological importance of seashells, advising against the collection of occupied shells to protect marine life. Additionally, participants are encouraged to engage in responsible collecting practices and consider the environmental impact of their actions.