“168 Lonely bleak islands off N.E. [New England] coast. Horrors they harbour—outpost of cosmic influences. (H.P. Lovecraft, story idea #168 in the “Commonplace Book”)
“There was a lone southward-sailing ship, and far out the eye could barely discern the misty suggestion of the half-fabulous Isles of Shoals [four miles off the coast from Portsmouth]. I had not seen the ocean before for six years—the glimpses one gets in harbours are nothing.” (H.P. Lovecraft, June 1922, Selected Letters I, p.185.)
“the low, black reef lay a full mile and a half out from Innsmouth Harbour.” … “Far out beyond the breakwater was the dim, dark line of Devil Reef, and as I glimpsed it I could not help thinking of all the hideous legends I had heard in the last twenty-four hours—legends which portrayed this ragged rock as a veritable gateway to realms of unfathomed horror and inconceivable abnormality.” (H.P. Lovecraft, “The Shadow Out of Innsmouth”)
Lovecraft had visited Portsmouth just one month before writing “The Shadow over Innsmouth”.
“They are supposed to have been so called, not because the ragged reefs run out beneath the water in all directions, ready to wreck and destroy, but because of the “shoaling,” or “schooling,” of fish about them, which, in the mackerel and herring seasons, is remarkable.” (Atlantic Monthly, 1869)
“the abundance of fish was certainly almost uncanny” … “Queer how fish are always thick off Innsmouth Harbour” (H.P. Lovecraft, “The Shadow out of Innsmouth”)
“As he [‘King’ Haley] turned over a stone one day [on his Haley Island, part of the ‘Isles of Shoals’] he found three bars of solid silver [and with that mysterious treasure built a sea-wall and a wharf]” (real-life story in “The Isles of Shoals”, Harper’s Weekly)
“always been a kind of mystery where the Marshes get the gold they refine … Others thought and still think he’d found an old pirate cache out on Devil Reef” (H.P. Lovecraft, “The Shadow out of Innsmouth”)
Of course Lovecraft probably never visited those particularly barren and low-lying Isles, only spied them from the coast and read of them. A visit entailed a full day-trip on a steamer from Portsmouth in the 1920s. The steamer landed passengers at the main Star Island, where the Oceanic Hotel was a church-run establishment and any cafes likely served quite expensive refreshments to a captive audience of trippers. So it’s more likely he just read up on them, then imagined that the most bleak of the Isles — such as the barren northern Duck Island and its ragged reefs and ledges — might be transplanted elsewhere, and brought closer in so that it would be clearly visible from a hideous old town.
Above: ‘The Isles of Shoals’ seen in relation to Portsmouth, 1917 topographic map. The map’s marking of “Town of Kittery” and “Town of Rye” across the islands indicates legal jurisdiction, not that the islands had towns on them. The hotel on Appledore island had burned down in 1914.
Curiously, given the supposedly ‘ever-rising sea levels’ that are supposed to soon inundate the nearby New York City, global warming has left completely untouched the coastline of these lowest of low-lying islands.