"The Haunted Beach" by Mary Robinson feels like a side tale to "The Rime of the Ancyent Marinere." Robinson even uses the term, "Shipwreck'd mariner." Again we has this visual of dead crew members and their spirits on board a ship while they are still sailing. The connection to "Ancyent Marinere" makes me wonder if Robinson and Coleridge knew each other, or if one person used the other poem as inspiration. If "The Haunted Beach" is a type of continuation, are the characters related? Who or what is the fisherman representing? In the other poem, the mariner had been the cursed one, cursed to tell his tale forever, but in Robinson's poem, the fisherman is doomed to "dwell on prospects dreary" for 30 years on that slate of land.
Something else I found interesting was Robinson's use of "green billows" in the last line of almost every stanza. I was not quite sure was "billows" was referring to, because original I imagine the billows being clouds, like "that billowing cloud". Green clouds sounded ominous, so it might have worked, but all I could then picture was a tornado, which did not seem likely with their proximity to the sea. I looked it up and learned that a billow could be "A great swelling wave of the sea, produced generally by a high wind; but often used as merely = Wave, and hence poetically for ‘the sea’" (OED). This definition made more sense. The billows are just incoming waves, crashing on the shore.
The think of the addition of "green" by Robinson in describing the billows created the scene. Most of the last lines say, "Where the green billows play'd." Green could just be the actual color of the sea, but it makes me think of a sickly color. Why green? Why not blue or teal? Maybe green indicates the ills that occurred. the sinking of the ship and the murder.