Panel, covering, and method for manufacturing such a panel

A panel comprising:

• a. at least one first edge and at least one opposite second edge, wherein said first edge comprises a first upper edge portion, wherein said second edge comprises a second upper edge portion;
• b. at least one first coupling part arranged on said first edge, and at least one second coupling part arranged on said opposite second edge, wherein the first coupling part of said panel and the second coupling part of another panel are arranged to be coupled to provide a locking of two coupled panels, such that at least a part of the first upper edge portion faces at least a part of the second upper edge portion to form a top seam in between the panels;
• c. wherein at least one upper edge portion, chosen from the at least one first upper edge portion and the at least one second upper edge portion, is provided with a channel-shaped recessed portion extending along the length of said upper edge portion, wherein the recessed portion is configured to adjoin an upper edge portion of an adjacent panel, in coupled condition of two panels,
• d. wherein at least a part of said at least one upper edge portion, located directly below said channel-shaped recessed portion, is provided with at least one expandable material layer, the at least one expandable material layer comprising at least one material configured to expand or swell upon contact with moisture,
• wherein an exposed portion of said expandable material layer is in direct contact with an atmosphere surrounding the expandable material layer;
• wherein the channel-shaped recess defines a bevel or grout line connecting an upper side of the panel and a side wall of the panel.