This application describes an overtube device that gives diagnostic and/or therapeutic access to body cavities using natural orifices of the body. The overtube includes an elongate flexible body having a distal portion deflectable in response to activation of a control cable. Proximal features of the overtube include an insufflations port and seals for minimizing loss of insufflations pressure around the shafts of instruments passed through the tube. In some embodiments, retractor elements are including on the distal portion of the overtube.