On a tiny island off Panama’s Caribbean coast, about 300 families are packing their belongings in preparation for a dramatic change. Generations of Gunas who have grown up on Gardi Sugdub in a life dedicated to the sea and tourism will trade that next week for the mainland’s solid ground. The Gunas of Gardi Sugdub are the first of 63 communities along Panama’s Caribbean and Pacific coasts that government officials and scientists expect to be forced to relocate by rising sea levels in the coming decades.