Because of it ability to absorb water
Why Does Water Have A High Heat Capacity?
Water is interesting in that it expands when it freezes, while most material contract, due to its dipole. In liquid state, the molecules are actually more closely packed than in an ice crystal. In liquid water, there is still a lot of space between the molecules. For example, 1L of alcohol poured into 1 liter water will result in ~1.7 liters of fluid with a greater density. That is because the alcohol wedges between the bent water's molecules.
Thermodynamics describes "degrees of freedom" that atoms in molecule have to oscillate. Between the density of water, and the spaces between molecules, it has a large capacity to store heat energy both in the internal vibration of the molecular bonds, and the kinetic energy of the molecules in the fluid. Bouncing off each other. In oil, for example, the lack of a dipole leaves no spaces between the atoms, so their oscillations are limited.
Thermodynamics describes "degrees of freedom" that atoms in molecule have to oscillate. Between the density of water, and the spaces between molecules, it has a large capacity to store heat energy both in the internal vibration of the molecular bonds, and the kinetic energy of the molecules in the fluid. Bouncing off each other. In oil, for example, the lack of a dipole leaves no spaces between the atoms, so their oscillations are limited.
Water has a high heat capacity because the water's temperature rise.