What are the relationships between volcanoes and geysers?

Both volcanoes and geysers depend on a strong heat source in the underground, but they have completely different mecanisms. A geyser is a phenomenon on the surface, where ground water beneath the shallow surface is heated up until it explodes into boiling water and steam and then refills its plumbing system with fresh water, so that a new cycle can start. Geysers don't need to be at a volcano, but almost always occur in volcanic regions close to a volcano. A volcano does not need to have geysers around.