Fluid motion that results from the release of potential energy from one of two or more factors that determine a fluid's density (for example, heat and salinity). Even if the density is statically stable, convection may result if one of the factors is statically unstable. There are three major types of double diffusive convection relevant to heat and mass transport in the ocean. Finger modes may occur when hot salty fluid overlays cold fresh fluid so that convection results in the form of narrow cells carrying salty water downwards and fresh water upwards. Diffusive modes occur when a stable salinity field is heated from below so that convection results in the form of a series of well mixed layers separated by sharp density gradients. Intrusive modes occur when there are horizontal density gradients in one of the components determining the fluid's density even if the fluid density as a whole is horizontally uniform. This instability develops in the form of interleaving intrusions.