The invention relates to a port marker which comprises lighting means and which is intended to be positioned next to the red and green light signals, lighting columns or lighthouses at the port entrance. The inventive marker comprises a self-supporting half-ring having a maximum height which is essentially greater than the height of the light source of the lighting column, lighthouse or light signal. The invention also comprises and electronic unit for powering and controlling the lighting means. The lighting means are distributed between the two ends of the self-supporting half-ring along the length thereof and are disposed such as to be visible to a boat or similar vessel approaching the port. The color of said lighting means corresponds to that of the respective obligatory lighting column, lighthouse or light signal at the entrance to the port, which, as mentioned above, can be red or green.