Actually not sure what it is, a number of suggestions made (See Mick’s theory), possibly erected to keep the Kiwi’s on their side of the ditch? (too late, I got through – lol!) Port Stephens, Tomaree Headland, NSW, Australia. A ‘Bubblers Meet’ with Mick. Nikon D7000, f16, 30sec, ISO 100, 18 mm, ND 400.