Ocean currents (and other water currents as well) are usually shown on maps to aid in naval navigation but can also be a neat way to visualize how water currents shape the environment for other purposes. (See Figure 6.49 for color suggestions.) Usually a current map will consist of text and symbols that convey the velocity and direction of currents on a given body of water (ocean or lake, primarily, but also applicable to rivers and streams if such data are available). Current direction is typically shown as arrows pointing in the dominant flow direction while velocity can be shown with symbol levels. Symbol levels can be made up of color gradients, line thickness gradients, and symbol gradients. For example, a darker blue and thicker line arrow could represent high velocity, whereas a lighter blue and thinner line arrow could represent low velocity. Another great way to show velocity is to create a map where