The present invention relates to a foldable and erectable boat, formed by four identical plane panels (1,2,3,4) in semirigid plastic material and with a shaped edge, which panels (1,2,3,4) are arranged in a longitudinal ordered adjoinment succession, so as to obtain two intermediate adjacent panels (2,3) and two outer or lateral panels (1,4), having a free edge. The two intermediate panels are adjacent and hingeably coupled to each other along one longitudinal edge thereof, while their other longitudinal edge is adjacent and hingeably coupled with a respective edge of an adjacent outer panel. Each panel is endowed with one or two grooves on both faces thereof, each groove extending parallel and proximate to one or both the longitudinal edges of the panel. The grooves proximate to the edges define an uninterrupted peripheral band or strip, which constitutes a portion joined to the panel by means of a double reduction in thickness, created by the grooves themselves. At the adjacent and coupled edges of two adjacent panels, the peripheral bands of the panels (1,2,3,4) themselves are fixed together, so as to form a sealing seam. Each panel is thus flexible or foldable with respect to the seam along the thinning or weakening represented by the grooves.