A hook, a hold down strap and a method for holding down an underground tank. The hook includes a base portion connectable to the hold down strap; a curved portion extending from the base portion and defining a concave receiving area having an entrance sized and configured for receiving an anchor element. The hook includes at least one hooking aid member being a flexible member or an extension member. The flexible member extends across the entrance of the concave receiving area and is sized and configured to bend from a closed position to an open position such that, when the anchor element traverses the entrance, the flexible member bends from the closed position toward the concave receiving area to the open position, thus allowing the anchor element to enter the concave receiving area. The extension member extends from the curved portion beyond the entrance of the concave receiving area.