An authorised person may, in performing a function or exercising a power under this Act, perform the function or exercise the power in respect of –

(a) any accretion from the sea, whether natural or unnatural; and

(b) any part of the seashore to the low-water mark; and

(c) any bridge, jetty, wharf, boat-house or other structure; and

(d) any area of the sea in, on, over or under which any building or building work is related to, or affects, any adjacent land.