Sailing hazards are a major concern for sailors, as they can cause serious damage to vessels and put lives at risk. Reefs, shoals, gales, and FOG are all common sailing hazards. A REEF is an underwater formation of rocks or coral that can be hazardous to ships. Shoals are shallow areas of water that can be difficult to navigate. Gales are strong winds that can cause waves to become choppy and unpredictable. FOG is a thick cloud of moisture that can reduce visibility and make it difficult to see potential hazards.