Yes, oceans can freeze.
Water freezes at a temperature of 32 degrees Fahrenheit (0 degrees Celsius), and the temperature of the water in an ocean can drop low enough for it to freeze, especially near the poles. The ocean’s surface can freeze to form sea ice, a layer of ice that forms on the surface of the ocean and is frozen seawater. Sea ice is most common in polar regions, such as the Arctic and Antarctic, but it can also form in other parts of the world, particularly during the winter months.
However, it is essential to note that the water in the ocean is saltwater, and salt lowers the temperature at which water freezes. This means that the water in the ocean needs to be colder than 32 degrees Fahrenheit (0 degrees Celsius) to freeze. The freezing point of seawater is about 28.4 degrees Fahrenheit (-2 degrees Celsius). This is why sea ice is usually thicker and more durable than freshwater ice, such as ice on a lake or pond.