Yellowstone Lake is probably one of the warmer lakes, though it is still very cold. The most signifigant part of this lake is the banks, which are made of pure grass. The grass stretches up from the depths of the waters, and travels steadily forward a good couple yards before forest takes over. When the lake grows, it takes over the grass, creating a soft floor. The lake is somewhat shallow, for a lake anyway. The edges slope steadily downward to the deeper water, and there are only a few signifigant drops that could take you by surprise here.