Extendable tunnel-type covering device

Extendable tunnel-type covering device, comprising a plurality of bow-shaped support elements (13) able to slide between a first position, wherein they define a first open condition of the cover, and a second position wherein they define a second closed condition of the cover, and a canvas (16) able to be associated with the bow-shaped support elements (13). At least part of the bow-shaped support elements (13) is able to alternately assume a first raised position and a second lowered position in order to temporarily vary the height of the space defined by the bow-shaped support elements (13).