This is the tale of two lovers, bound to each other through time and perhaps even space – who are destined to struggle to find each other and love each other in various eras; pre-world war II Germany, 15th Century Egypt, a lost island kingdom, and even the distant future, and the one thing that always connects them is the sea…

source: https://www.mangaupdates.com/series/ccr2uca/umi-no-aurora