Underwater lighting is divided into 2: 1) Continuous lighting 2) Flash Lighting  .

Continuous lights are lights usually used for video, there are an abundance of lights in the market , some powerful enough to even be used for stills shots ( 2000 Lumens and over). Click here for our Underwater Video Light Guide

Flash lighting is better for stills shots as the strong burst of light provide the camera with the amount of light it needs for exposing the picture to the photographers preference.  The downside of using this method of light is that there is no way to view the picture before it is taken , i.e. one needs to take many shots until the perfect exposure is reached.

Click here for our Underwater Strobe Guide

Most customers use a DSLR with 2 strobes such as this one :Sea and Sea YS-01 and one Video light such as this one: Light and Motion SOLA 1200

If you do a lot of video , I would recommend 2 video lights for more power and a wider angle.  the 2 strobes are strongly recommended for getting enough angle of light on wide shots.