Surgical devices having a plurality of outwardly-biased flexible fins capable of inward movement such that the fins converge to provide both a passageway for surgical instruments to traverse towards a surgical site, and provide a substantially impermeable seal, thus providing for fluid retention during the surgical procedure. The outwardly-biased flexible fins provide for soft tissue compression, decreasing the length of the lumen or passageway through which instruments pass, allowing for a wider range of movement of instruments and better access to the surgical site, especially in patients with greater amounts of fat tissue that would otherwise require longer lumen lengths in prior art endoscopic cannulas.