In maritime navigation, an area where rocks are just below the surface is often referred to as a "shoal" or "shoal water." A shoal is a submerged sandbank, coral reef, or rocky area that lies close to the surface of the water. These shallow areas can be hazardous to ships and boats, as they pose a risk of grounding or damaging the vessel.
Shoals can be found in various bodies of water, including oceans, seas, lakes, and rivers. They are typically marked on nautical charts to alert mariners to their presence and assist in safe navigation. Special navigational aids, such as buoys or beacons, may also be placed near shoals to provide additional guidance and warning to vessels.