 Another problem concerned the color of the water in the pond holding  the boat; it was too brown and murky. They hired a chemist to  develop a dye to color the water Azure Mediterranean blue. The  chemist dumped a huge sack of some powder into the pond, which,  instead of turning the water blue, formed a hard crust on the  surface of the water, which had to be chiselled off the boat at  great expense. They finally found some dye that would make the water  blue. During one of the battle scenes, an extra who fell into the  water and spent a bit too much time there turned blue, and was kept  on the MGM payroll until it wore off.