Abstract: An offshore terminal mooring buoy of the cantenary anchor leg mooring (CALM) type includes a buoy which is designed to dive at an angle downwardly through large swells during bad weather. The buoy has a wedge shaped side cross-section including an inwardly angled upper sidewall that not only causes the buoy to dive through large swells, but also reduces its drag coefficient so that undue stresses will not be placed on the buoy's anchor chains as it dives through the water. The bottom submerged portion of the buoy can also incorporate a wedged shape to decrease its drag coefficient further. Preferably, the buoy also has a hexagonal shaped top cross-section which further reduces the buoy's drag coefficient, and makes the buoy easy to fabricate.