What penetrates deeper in water? Blue or voilet? I was wondering about what colour of light penetrates deepest, and stumbled upon this pic while reading about related content.

The pic shows, violet is penetrated to a lesser extent than blue. 
If this information is right, what could be the possible explanation? 
If light with higher energy penetrates deeper, then violet should reach to greatest of depth. Or is it because water absorbs violet light?
 A: The Wikipedia article on light absorption by water includes this graph of absorption in the visible region:

The minimum absorption, and therefore the greatest penetration is around $\lambda = 420$nm, which is on the boundary between blue and violet light.
However the spectrum of sunlight looks like this:

(picture from here)
Note that the intensity of sunlight peaks between $\lambda = 500$ and $550$nm and it falls rapidly at smaller wavelengths. So even though water absorbs least at violet wavelengths the light intensity decreases because there isn't that much violet light in sunlight.
The maximum penetration at around $\lambda = 475$nm is a trade off between the decreased absorption and decreased intensity as the wavelength decreases.
A: I believe the conflicting wiki graphs (mentioned in the last comment) originate from the exact definitions of absorption (e.g. if scattering is taken into account, what type of light source etc.) as well as whether you use a theoritical model or empirical data.
This page https://omlc.org/spectra/water/abs/index.html suggests that the minimum is now around 420ish nm, close to Rennie's answer. The convolution of that absorption curve with the solar spectrum (which also depends on time, location, conditions etc.) at sea level, combined with the various water conditions can be turned into a practical answer (for divers, submariners etc.) of roughly 475nm. Probably plus or minus 20nm depending on the conditions I mentioned.
