It is almost like relationship between humans
« The reason we feel water-resistance in swimming pool is because of water’s viscous properties. The H2O molecule is lonely and seeks to hold hands with other similar molecules creating a network that forms a hydrogen bond. A water molecule consists of two hydrogen atoms covalently bonded to a single oxygen atom, thus creating a 104.5 – degree angle. The important thing to know here is that water molecules never stand alone as elementary substances, but always connect with neighboring water molecules. The water molecule is tiny : 3x10-10m (3/10000 of micron) in diameter, and the speed of connection and disconnection with its partners is as fast as one per trillion of a second […]. »

Taku Satoh, « water », with the contribution of molecular scientists Shinji Saito and Masakazu Matsumoto.
Vittorio Fragasso