Besides the land regions (Balenos, Serendia, Calpheon, Mediah, Valencia and Kamasylvia) of Black Desert Online there is a large waterworld to explore. This includes the islands of the world as well as the oceans themselves.
Travel between the islands and continent is possible by private boats or ships or public ones on a schedule. Trade ships can move items for the player as well against a fee. Pirates roam the oceans and can cause havoc the same as thieves on land when one is moving trade goods. Soon naval battles will be available.
And there is a rich underwater landscape that can be explored.