Abstract: Apparatus for casting light alloys in water, of the type including a cooling water tank used in order to cool a die or ingot mold inserted under tight sealing conditions inside the water tank, and anchored to the water tank. The apparatus uses a water tank which is arranged separate and spaced apart from a casting basin such as to create an air space between the cooling water tank and the basin. The die has a cap or sleeve, inserted inside the water tank under tightly sealing conditions, which have a length that a portion thereof will protrude above the top plane of the water tank. This forms an annular, raised edge, which is high enough as to prevent any possible water leaks between the water tank and the die. Water is prevented from flowing above the annular edge and penetrating the die, consequently causing explosions and/or the projection of liquid metal jets through the casting channel.