South and North Thormanby - sx̱welap together - lie within the shared territories of the Tla'amin Nation and the shishalh Nation. The bay that Richards named for a racehorse held klayahkwohss, a village that served as a principal site for winter dances and ceremonies, along with sex̱wʔamin at Garden Bay to the north. Winter on this coast is the ceremonial season; the fishing and gathering year ends and the longhouse year begins. At least five archaeological shell middens are known on South Thormanby, the accumulated kitchen record of generations - clam and oyster and mussel shell packed metres deep, which is how you date continuous occupation on a coast that keeps few other monuments. The village names are still in use. So is the language they come from.

The island is built around two rises: Mount Seafield at the southern end and Spy Glass Hill toward the north. South of Seafield, in a basin locals simply call The Farm, there is a lake. The south island is markedly rockier than its northern neighbour, and at low tide the two connect by a sand bridge you can walk across - a detail that makes the pair behave like one island twice a day. Welcome Passage separates the group from the mainland shore of the Sunshine Coast. Mariners pay attention to Tattenham Ledge, a long shallow rock shelf reaching out from the island's northern side and a genuine hazard rather than a charted curiosity. Pirate Rock and Merry Island - nepshilin in she shashishalhem - sit off the southern end.

In 1892 Calvert Simson, who kept shop at the Hastings Mill Store in Gastown, secured rights to most of South Thormanby through a crown grant. Around 1912 he drained and cleared the southern swamp to make a farm and orchard - an ambitious thing to attempt on an island with no road and no neighbours. The farm was abandoned in 1948; the buildings came down through the 1960s and 1970s. But semi-wild apple and cherry trees still fruit in that clearing, which is the most persistent thing anyone ever left here. Through the 1920s and 1930s the Union Steamship Company ran a float in Buccaneer Bay and made regular sailings from Vancouver, and trails were cut and bays named in that era. Selective logging ran from 1951 to 1981, taking mostly Coastal Douglas-fir. In 1986 the southern part of the island became Simson Provincial Park, named for the shopkeeper.

British Columbia sorts itself into sixteen biogeoclimatic zones, and the Coastal Douglas-fir is both the smallest and the most imperilled. It holds more species at risk than any other - twenty-four of them globally imperilled, 282 provincially listed, plus forty-four ecological communities in trouble. Thormanby sits squarely inside it. Along Buccaneer Bay and Vaucroft Beach a rare coastal sand ecosystem supports two further red-listed communities: large-headed sedge, and dune wildrye with beach pea. Inland the forest is second growth now, Douglas-fir and western red cedar with hemlock, red alder, arbutus, lodgepole pine and bigleaf maple mixed in, and an understorey heavy with salal, salmonberry, thimbleberry and huckleberry. Roughly three hundred Columbian black-tailed deer live on the islands. Beavers were introduced in 1984 and 1985, promptly dammed the old Simson meadow, and made the lake that is there today.