An underwater light show...

Yes that's true, I saw a Cranchi motoryacht in holland last week with underwaterlights, the water was verry brown cause in was verry hot for a long period, so the water was ful of algies and dead plants.

The most beautiful are the lights in nice clean water like the Mediterrean or carribean etc, like the picture of Andromeda La Dea and the Azimut.

There's no end to some people's vanity when it comes to lighting up their superyachts I guess...? I've no objections to that in port, but a few come immediately to mind when they're anchored out in some other places:

1) A lot of the reef fishies are probably trying to get some sleep at that time of night (the ones that survived the 500kg anchor and 100m of Ø18mm stud-linked chain being dropped "out of the blue") onto their villages...and doing their best to escape attention from the night-time predators in what might normally be obscurity.

2) The few astronomically-inclined fishies amongst them might also appreciate a few hours of relative darkness without having to seriously consider moving to a Chilean mountain-top in order to pursue their interests in heavenly bodies...

some more pictures

Can't say I have ever seen underwater lights on out of the water. Aren't you only suppose to have them on while they are submerged?

I notice that some Yachtfishers have ample lights as well as traditional Yachts. Do some use them to attract fish to the boat for night fishing? and if so, is this common practice.

Yes the double hull craft has also the underwaterlights, I have some more pictures somewhere of that craft, will post them also.