In which oceanic region are water molecules generally slightly expanded due to warmth?

Water molecules tend to be slightly expanded in warmer regions due to the increase in kinetic energy as temperatures rise. At the Equator, the ocean receives more direct sunlight and experiences higher temperatures, leading to thermal expansion of water molecules. This phenomenon is known as thermal expansion, where water's density decreases as its temperature increases. Consequently, in equatorial regions, the water is generally less dense and slightly expanded compared to cooler areas, such as the poles or higher latitudes, where temperatures are significantly lower. In these cooler regions, water molecules remain more closely packed due to reduced thermal energy, resulting in a higher density and no significant expansion. Thus, the Equator, with its warm waters, is where water molecules are most obviously expanded.