Leak-proof and unbreakable panel comprising a locking element, and method for producing such a panel

A panel for covering a surface of a room, comprising

• a panel element extending in a longitudinal direction and in a transverse direction for transferring use loads introduced at an upper side of the panel element to a lower side of the panel element facing the surface of the room, wherein the upper surface is spaced apart from the lower side in a thickness direction;
• a retaining groove extending in an end face short side of the panel element in the transverse direction;
• and
• a locking element inserted into the retaining groove, in particular immovably, wherein,
• for an extension b0 of the retaining groove in the transverse direction with respect to a nominal width B of the panel element between a first edge of the panel element extending in the longitudinal direction and a second edge of the panel element extending in the longitudinal direction 0.50≤b0/B≤0.97, wherein a first reinforcing area with an extension t1 in the transverse direction is formed between a first end of the retaining groove facing the first edge in the transverse direction, wherein a second reinforcing area with an extension t2 in the transverse direction is formed in the transverse direction between a second end of the retaining groove facing the second edge in the transverse direction, wherein for the first reinforcing area 0.005≤t1/B≤0.090 and/or for the second reinforcing region 0.005≤t2/B≤0.090.