The Great Barrier Reef is a natural wonder which can be found on coastal ocean tiles. Unlike other natural wonders, the Great Barrier Reef covers two hex tiles that are adjacent to each other. These tiles cannot be entered by ships, boats or embarked units. As the tiles are adjacent, a civilization easily gets the discovery bonus twice, which can be an incredible boost for the Spanish. Also, each of the tiles can be worked separately, and each provides the stated bonuses, effectively doubling the Wonder's output.