Walk barefoot across a beach on a sunny day and the sand can feel extremely hot, while the nearby sea remains much cooler. Both have received energy from the Sun, but their temperatures do not rise by the same amount. One reason is a property called specific heat capacity. Specific heat capacity is the energy required to increase the temperature of one kilogram of a substance by one degree Celsius. Water has a relatively high specific heat capacity. A large amount of energy must therefore be transferred to water to produce a given temperature increase. The sea also moves and mixes. Waves and convection distribute energy through a much larger volume of water instead of leaving all the energy near the surface. Evaporation can also transfer energy away from the sea. Sand behaves differently. Solar radiation can heat a relatively thin surface layer, causing its temperature to rise rapidly. At night, the difference can reverse. The land may cool quickly while the sea remains relatively warm because its temperature changes more slowly. This helps influence coastal weather and climate. Specific heat capacity also matters in engineering. Water is commonly used as a coolant because it can absorb a large amount of thermal energy without an enormous increase in temperature. A beach therefore provides a large-scale thermal physics experiment: receiving similar sunlight does not mean different materials will reach the same temperature.