The Soufrière Hills Volcano is the only active volcano in a UK territory, situated on the southern half of the small Caribbean island of Montserrat. It is a type of volcano that forms lava domes: the magma rising from deep inside the earth is particularly thick and viscous, creating a hot crust of blocky lava at the surface. During the day the heat cannot be seen because the surrounding light is too strong, but when night falls the hot parts glow red showing where the dome is most active.