It may be such that when you want to increase the heat content of water externally by changing the temperature,as specific heat capacity of water is high it will require more amount of heat in comparison to any other substance of same mass and same change in temperature.
Suppose heat required is
So,we can write,
As, S water>S object
So,you can have the idea that water gets heated the last than any other substance and you can explain from this why the sand of beach gets heated earlier than sea water.