Shoot of a popular beach in Algarve, Portugal. The tide was really low which allowered to get quite close with the double arches. The black patches in the water are big chunks of seaweed that were floating with the waves.
Shoot with an old Sigma 17-35 mm F2.8-F4.0 at 17mm. This lens has a Nikon mount, but I use it on a Sony A7 with a manual adaptor, so I never sure of the aperture used.