Sodium. Keep in mind that it will explode, though.
Here is fire from water, and here are several methods of fire from ice.
Any of the Alkali metals will react with water to create either a flame or an explosion depending on how far down the periodic table of elements you go. Sodium and Potassium form flames and should be capable of starting a fire but as you work your way down they get more and more dangerous.Keep in mind however that although these methods might work to get a fire started using water the presence of water will probably hinder whatever tinder you are trying to ignite.
i once watched an episode of mythbusters,where they froze a small bowl of water next to a vibrating machine(to make it freeze clear) then using ice like a magnifying glass with the sun were able to start a fire
Of course! I have one word for you.