Wavelength and depth

Hopefully this 2nd picture can help explain more clearly to my dear friend Bee Leng.

As the waves get closer to the shore ( which is shallower) the distance between successive white crests ( called wavelength) become smaller.

When the waves are further from shore as in the deeper waters, the wavelength is much bigger.

I am updating this post 12 years later with some lovely photos of Kiama Bay near Sydney, courtesy my friend Wee Lai who stays near there.( 27th August 2022)

Can you see the wavelengths changing as the waves approach the shore?

Can you see the surfers riding the crest of the waves? The distance from one crest to the next crest is the wavelength. The bigger the wavelength, the deeper the water and the higher the velocity of the waves.