Groynes are just under water at low tide. Also the beach for the groynes is just under water, at the beginning still see the shells and stones through the sea water.
B+W ND110 - 10 stops.
Lee neutral density soft grad filter 1 stop
Lee neutral density soft grad filters 3 stops
140s (2min20s) exposure
Nik Software Silver Efex Pro 2
Nik Software Dfine 2.0