The term "turquoise waters" is a figurative expression that refers to the beautiful, vibrant blue-green color of ocean water in tropical or subtropical regions. The word "turquoise" comes from the French word for "Turkish," as this particular shade of greenish-blue was first brought to Europe by trade with Turkey. In essence, when someone refers to "turquoise waters," they are describing water that is a bright and inviting shade of blue-green, often associated with warm weather, sunshine, and sandy beaches.