"White horses" are the white, foamy crests of breaking waves caused by strong winds, acting as a visual indicator of wind speed and sea conditions for sailors. They typically appear at Beaufort Force 3-4 (roughly 7–15 knots) and become numerous at Force 5-6, signaling a need to prepare for rougher water or reef sails.

Key Details on White Horses (Whitecaps):
Definition: They are the white foam created when wind breaks the top of waves, often described as "whitecaps" or "little sheep" (in New Zealand).

Sailing Impact: They indicate a "blown out" or choppy sea surface, often making conditions uncomfortable, requiring sailors to reef the mainsail (reduce sail area) to avoid being overpowered.

Formation: They depend on wind speed, duration, and fetch (distance wind blows over water).

Folklore and Origins:
The term is deeply rooted in maritime culture and mythology:

Mythology: In some legends, breaking waves were seen as white seahorses carrying Poseidon's forces.

Regional Names: While "white horses" is common in British English, American sailors more frequently use "whitecaps". Other cultures use similar animal metaphors, such as the French moutons (sheep) or Japanese "jumping rabbits".