Underwater LED lights with enhanced cooling to allow the use of substantial numbers of high power LEDs. In all embodiments, the majority of the heat given off by the LEDs is transferred to the housing of the underwater light by heat transfer techniques other than by convection of the air or other gases within the enclosure, providing direct heat conveyance from the LEDs to or through the light enclosure walls, by conduction through a thermal conductor or by or as augmented by heat pipes to the inside wall of the enclosure or through the wall of the enclosure to the water. Various embodiments are disclosed.