The red algae , can survive at 4000 m deep , without light.
Most blue algae need light, in order to life. In waters, the light radiation is absorbed which means that in lakes with the depth around 10m, only about 10 %, in the ocean, at depths around 100m, only about 1% of the light intensity is available. Despite that, there are still some algae, which can survive in 4000m deep ocean basins. These however aren’t blue, they are red- violet coloured, the reason why the Red Sea got its name. The assimilation reaches its upper boundary at temperatures around 65 degrees Celsius. In the hoisting sources of mineral, the blue algae are the only "settlers", which lead assimilation and are actively viable up to temperatures around 75 degrees. Interesting is however, that the blue algae do not grow at temperatures under 30 degrees Celsius. But there are also many blue algae, which can bear very low temperatures. Thus, they occur in the Antarctic under the conditions of the extreme heat lack (temperatures around -88 degrees Celsius). Because the blue algae possess the possibility of binding nitrogen, they can easily adapt to almost each ecological condition, which could be the reason why the algae are predominant in our waters.
http://library.thinkquest.org/27115/pages/algae/algae_bottom2.html