The Mk5 offers four types of doors (domes and flat):

1. HydroFlex Standard Dome Port: This is the same dome design that HydroFlex designed and manufactured for the Cousteau Society's 35mm cameras. It became an industry standard for many years, with hundreds of credits in major box office hits.
   

2. 250mm Dome Port: The use of this dome is advantageous due to its larger diameter; lenses do not require such a close focusing distance to focus on the aerial image created by the port.
   

3. HydroFlex Standard Flat Port: Standard item in RAC boxes. It is used for close-ups with longer focal length lenses underwater, for filming above water, split-level shots, or when the shot transitions between underwater and surface environments.
   

4. Large Flat Port for RAC: With the proliferation of larger sensors and lenses with wider viewing angles, the Large Flat Port may be necessary as an additional item.