Water is generaly found on the surface of maps but it can also be found underground. Water can spread, so destroying blocks in its path will allow water to "Grow". Water can be transported by Buckets and placed in a different location. If Water touches a Lava source, it will turn into Obsidian. If it touches Lava which isn't a source it will turn into Cobblestone. Water can extinguish Fire, making it an ideal place to jump into if your on Fire.