Low tide at Sanna reveals great expanses of sand across which to wander, space shared with....
....the gulls and the occasional wader, like this ringed plover.
In places, the upper beach is cut by the meandering courses of the burns where they flow out onto the sands. Over the generations, the drier, looser sand has been blown inland by the westerlies to form dunes covered with marram grass - the machair.
Port na Tuine lies at the southern end of Sanna's series of bays. It's more confined than the other bays, and faces straight out to the ocean, so it experiences the heaviest waves. During last winter, they removed much of the sand from the area of the beach in the foreground of this picture - and then carefully replaced it.