Why there are no waves in rivers but there are in sea?

This would require us to first know what a wave is exactly. A wave is formed on an expanse of water mostly due to strong winds blowing over the surface of the water body. There are some conditions for waves to form in this way by winds. read more

tl;dr: Waves in rivers are on average smaller than waves at sea or in oceans because rivers are much, much, much, really quite much, rather very much smaller bodies of water than lakes, seas and oceans are. read more

The Gravitational force of Moon acts on Rivers too. But, as they contain lesser quantity of Water than the Oceans, Waves do not form on Oceans. read more