Aquanaut Chronicle

In a world surrounded by water, humanity now resides in underwater towns as known as "shelters". A teenager named Ur together with his childhood friends Meryl and Sivajas operates a delivery business. One day, Ur rescues a girl who lies unconscious on the seabed. The mysterious girl who calls herself Avi is actually a member of the southern royalties. After several struggles, the gang decides to transport Avi to the Empire State, hence beginning their life threatening journey.