Uncharted Waters, or Daikoukai Jidai, is a strategy simulation game from Koei set during the Age of Discovery (15th-17th century) in which the player is a neophyte ship captain from a disgraced noble family, out to make his fortune and restore the family name to its proper station. The player can sail around and discover ports belonging to either of the game's three nations - Portugal, Spain and the Ottoman Empire - as well as politically neutral ports. These neutral ports can be invested in to increase the player's wealth and reputation. The end goal of the game is to build the player character's fame through discoveries and by winning ship battles with pirates and rival merchants, which eventually allows the player to take on tasks for the King of Portugal who will restore the player's nobility in gratitude.

Uncharted Waters was released on the NES and MSX originally, though versions for SNES, Genesis and PC followed soon after. The series received a few sequels, though only the first sequel - Uncharted Waters 2: New Horizons - was localized and released in the West.