When a whale or dolphin swims at shallow depths, turbulence from its flukes rises to form a circular slick on the surface: the footprint or flukeprint.

• 当鲸鱼或海豚在浅水中游动时，海水在它们尾鳍的搅动下，表面会涌起一个圆形的平滑水纹：这便是它们的“足迹”或“尾印”。