Is the dead body's remaining submerged in water considered a ghusl for it, or must it be washed before shrouding and praying over it?

Washing the deceased is obligatory, and it does not become waived if the person dies by drowning. So, the man should be washed before shrouding him and praying over him. If his body has changed, it suffices to pour water over him without passing the hand over him.