This happens because the amount of sunlight and hence energy from the Sun that reaches the earth's surface is a function of LATITUDE. Because of the tilt of the earth's spin axis with respect to the plane in which the Earth revolves or orbits the Sun, the CONCENTRATION of sun enegy or the energy per square meter of land VARIES with latitude. The low latitudes get more of the suns energy. This causes unequal heating and the oceans respond to that.

There are several reasons for this, but the most important is sunlight. The closer the sun is to being straight up, the more light you get, and the more heat you get. At the equator, the sun is usually straight up or very close, while at the poles, the sun This is why the equator is warm and the poles are cold.

Great question! The earth's surface is warmed by the sun which focuses its energy around Earth's equator, so land and water near the equator will be warmest. The interesting thing about the relationship between the earth and the sun is that Earth's rotational axis is tilted and wobbles toward and away from the sun, so sometimes the North pole is pointed toward the sun, and sometimes it's pointed away from the sun...this is why we have seasons! So, seasonally, when the North pole is pointed toward the sun, we have Northern Hemisphere summer, and Southern Hemisphere winter.

The temperature of a body of water can also change depending on the source of water, the depth, and other processes. For example, a high-latitude lake could change temperature wildly over the course of a year -- it could be frozen in winter, but warm and swimmable in summer. Whereas the ocean is so large, the seasonal temperature range is fairly narrow compared to lake or river temperature ranges.

The sun is stronger in some parts of the world, and it heats up the ocean. The warmer ocean currents are near to the equator and the colder ocean currents come from the north and south poles.

Water (and air) temperature has to do with the amount of sunlight that certain part of the world receives. Towards the equator, sunlight hits the Earth at a ~90 degree angle. On the north and south poles however, sunlight hits the Earth at a much smaller angle see picture . This means that at the equator, one beam of sunlight is concentrated on a small area, whereas at the north pole, one beam covers a much larger area. The equator therefore receives much more intense sunlight than the north/south poles, making the water at the equator warmer.