Expect Rougher Caribbean Seas in the North and East Rough Waters: When one body of water runs into another, waves tend to be higher and rougher. Although the Caribbean is generally known for smooth sailing, it can get choppy in areas where it meets up with the Atlantic Ocean.

Whether the Caribbean waters are "calm" depends largely on the specific island's geography and which side of the island you are visiting. Generally, the Caribbean Sea (Western) side of an island is much calmer and clearer than the Atlantic (Eastern) side, which is exposed to open ocean swells and stronger winds. Islands in the "Leeward" chain or those protected by large coral reefs—such as Aruba, Bonaire, and Curacao (the ABC islands) or the western shores of the Cayman Islands—are famous for their glass-like, tranquil conditions year-round. Conversely, the "Windward" islands like Barbados or St. Lucia have significantly rougher Atlantic coastlines that are popular with surfers but less ideal for casual swimming. Seasonality also plays a massive role; during the winter months (December to March), "north swells" can occasionally bring larger waves to northern-facing beaches. During hurricane season (June to November), the waters can change from perfectly still to dangerously turbulent within hours, though the ABC islands remain the safest bet for consistently calm waters as they lie south of the main hurricane belt.