Light fixtures for illumination of liquids in a variety of environments. In one example, multi-color LED-based light fixtures are employed to achieve a wide range of enhanced lighting effects in liquids. In another example, a pool or spa is illuminated by one or more multi-color light fixtures that may be employed as individually and independently controllable devices, or coupled together to form a networked lighting system to provide a variety of programmable and/or coordinated color illumination effects in the pool or spa environment. The light fixtures may have a significantly thin depth dimension to facilitate streamlined mounting in the pool or spa. Additionally, the light fixtures may be particularly constructed to take advantage of the liquid in contact with the light fixture so as to facilitate the dissipation of heat generated by the light fixture.