Thanks for answering.
The reason for my question was I noted the tell tale rectangular shaped specular reflection in the sunglasses of the woman camera right, here:
Noting this, I was 99% sure that you used a
Direct Flash that was Camera Mounted (aka "a speedlite on the hotshoe"), . . .
BUT - I could not see any evidence of Flash as Fill. That is to say I could not see any evidence of shadows on the faces being filled or shadows being created by the Speedlite.
Then I had a quick check of the Tech Specs and you mentioned that you use 70mm - why I wanted to know the camera format and if the image was cropped, was to estimate the SD (Subject Distances).
With a 70mm lens on APS-C you'd be at about 12 ft to pull that shot.
With a typical (High-Powered) Speedlight we only have a FWD (Flash Working Distance) of about 12ft to fill in backlit, hard sun.
So, I then concluded that you were at the edge of the Flash's Working Distance Limit - even if you have a powerful speedlite like an SB800 or SB900.
Certainly with the additional information I cannot compute how at 1/32nd power there would be any effect from the flash.
***
This is a bit earlier in the afternoon, but the rules of engagement for Flash as Fill in backlit sun remain the same:
Note firstly that the AMBIENT EXPOSURE of the back-ground sky and water is made 'correct'.
And then I had to make the Flash's WORKING DISTANCE close enough, to ensure that I had enough FLASH POWER to FILL the Subjects'
in shadow areas to match the Ambient Exposure.
To ensure that I had enough power
I was working at about 8ft, and I was using an APS-C camera and a 16 to 35 lens.
Knowing and working within the Flash Working Distance is most critical for Flash as Fill, especially for Flash as Fill in backlit sun, as this is one of the most demanding Flash as Fill situations.
WW