Which of the following are examples of natural navigation aids divers may use during dives?

Natural navigation aids for divers refer to features in the underwater environment that can help in orientation and determining position without relying on artificial tools. Ripple marks in the sand and bottom contours are both excellent examples of such aids. Ripple marks, formed by water currents, can provide insights into the direction of flow and help divers maintain a sense of navigation relative to those currents. Similarly, the contours of the seafloor—such as slopes, trenches, or ridges—can guide divers and assist in understanding their location within the underwater landscape.

These natural features can be easily observed during a dive and often remain consistent over time, making them reliable aids for navigation. In contrast, underwater maps and compasses are tools that provide information but are not considered natural aids. Buoys and lighthouses are man-made structures, and while they serve a navigational purpose, they do not fall under the category of natural aids. Fish schools and wave patterns can also be relevant to understanding the environment, but they are less reliable for navigation compared to the persistent and recognizable features like ripple marks and bottom contours.