spex goggle for surfing rarely fogs
Mauricio surf sunglasses reduce fogging
Surf Sunglasses
Surf Sunglasses Ventilation to Prevent Fogging
Surf Sunglasses Fogging
There is no point in wearing sunglasses if you cannot see out of them - it can be a real nightmare if your surf sunglasses lenses fog up!  In tropical waters, fogging is not an issue but when there is a huge temperature difference between your face and the water (which chills the lenses) fogging can be problematic.
Ventilation Is The Best Way to Minimize Fogging
If you surf sunglasses are well ventilated they will fog much less.  Proper ventilation allows the lens and air temperatures to equalize quickly.  When the lens returns to air temperature fogging disappears. 
Sunglasses for Water Sports With the Best Ventilation
Spex Goggle for surfing - The lenses only attach to the frame in the corners, leaving the rest of the area open to air flow.
Mauricio Sunglasses for surfing - The Frame is wide open on the bottom allowing for the air to flow freely. 
Sunglasses for Water Sports
surfer with sunglasses for surfing
WearSurfGlasses.com is the Surf Sunglasses Super Store
Different models use different technique to increase ventilation.  The Fuerteventura and the Costa Rica have holes in the lenses to increase ventilation.  Many surf sunglasses like the Seaway and the Australia have holes in the frames to promote ventilation.  These mehtods have limited effect but better than nothing.
The Tierra del Fuego have a very special design.  The foam padding sits on a hard plastic backing with many ribs and channels.  The ribs rest against the frame leaving a plethora of channels for air and water to flow through.  This is an innovative and effective approach to ventilation.
The Mauricio successfully reduces fogging by attaching the lens only to the top of the frame and leaving the bottom of the lens completely open.  This works really great for people with small cheek bones.  If you have large cheeks then you may block the area where air should flow through.
The Best Surf Sunglasses to eliminate fogging in cold water
The surf sunglasses that most sucesfully eliminate fogging are the Spex Surf Goggles.  The lenses are attached to the frame only on the corners, the rest of the frame is there to support the lens but allows ample air to flow between the lens and the frame.
Tierra del Fuego's innovative approach to ventilation
The Tierra del Fuego use an innovative and effective approach to ventilation.