The first option is to get your waterway glowing. I suggest submersible HID lights that are installed 5' below the water and about 7' away from the dock. These lights will produce a light ring about 40" in diameter. The installation is simple and can be done by anyone that can plug in a electric cord.
The second is what we call pathway lighting. These lights must be installed by an electrician but are low voltage so no worries about anyone getting a shock. These lights a placed directly on the dock and give a glow to the left and right of the fixture to illuminate your dock or deck.
There are also underwater lights that mount to the pilings. These lights are generally LED and and you would need to have 1 light on each piling to get a nice even glow in the waterway. Manufacturers such as OceanLED, Aqualuma and Lifeform LED offer these lights. They are not cheap but, the look is beautiful.
How you decide to illuminate your dock is going to be based on budget but more importantly the look you are going for. Check out www.lumasea.com for all of the lights discussed. You will be surprised whats living in the water behind your house.