There are many natural navigation aids you can use while diving. When diving near shore, waves create navigation aids that indicate the direction towards shore. One example is ripple marks in the sand, which run parallel to shore and become larger as you swim closer to shore. Additionally, waves create a back-and forth movement of water called surge, and this movement is usually perpendicular to the shore.

Depth is another navigation aid. Near shore, you can tell if you're swimming towards shore if the depth decreases. Or if you know a boat's anchor is at 60 feet, you can swim to a depth of 60 feet and follow bottom contours to locate the anchor.

Landmarks such as reefs and artifacts are valuable navigation aids. And if these landmarks cast shadows, you can navigate based on the direction those shadows are cast.

When boat diving, the boat may be visible during your dive, so swim towards the boat to locate your ascent location. If the boat is anchored, the anchor line provides a valuable navigation aid that you can follow to locate the boat.