It was basically a great chest, or box. Jehovah gave Noah the precise dimensions of the ark, some details regarding its design, and directions to coat it inside and out with tar.
وقد حدد يهوه بدقة قياسات الفلك وأعطى نوحا تفاصيل عن تصميمه وأمره ان يطليه من الداخل والخارج بالقار .‏