The symbol for water and waterbending is a circle comprising a stylized rightward-facing ocean wave with three spiral crests breaking over three wavy diagonal lines representing water.

The Avatar Symbols represent the Four Bending Nations and the elements they bend. They are fire, air, water and earth. Bending is the ability to manipulate an element.

Iroh drew the symbols of the bending arts in the dirt. The four elemental bending arts are based on the four classical elements, water, earth, fire, and air, each being manipulated through certain martial art styles that are reminiscent of the qualities of the element itself.

The world is traditionally divided into four nations: the Water Tribe, Earth Kingdom, Fire Nation, and Air Nomads. Each nation is culturally unique and associated with one bending technique: waterbending, earthbending, firebending, and airbending, respectively.

Thats right, that's the water tribe emblem, and the one with the 3 rolling waves atop the circle is the water element. As for the airnomads, they have one spiraling circle, and the Airbender has the 3 spirals of air