Pori's merchants put up the first marker in 1779, a wooden daymark meant to keep their ships off the rocks, and a hexagonal replacement followed in 1852. Neither carried a flame. That came in September 1873, when a brick tower designed by Axel Hampus Dalström was lit for the first time: a two-stage tapered cylinder rising 28.21 metres, its lamp burning 34.8 metres above the water behind a Fresnel lens. Keepers and their families lived at its foot for nearly a century. Automation arrived in 1962 and emptied the houses, though the light itself has never stopped. It still marks the approach to Pori, running now on solar panels and looked after by a local association rather than a crew.

The Reposaari hunters have leased the old pilot cottage since the late 1950s, and the mouflon are their doing. Introduced sheep on a small island cannot simply be abandoned to themselves, so the club has managed the herd ever since, taking a few animals each autumn. It is an odd arrangement to explain and a remarkably durable one — more than seventy-five years of Mediterranean wild sheep wintering at sixty-one degrees north. Visitors who come out for the lighthouse often meet them first, standing at the edge of the trees with those heavy curled horns, entirely unbothered by the arrival of a boat.

In 1959 the lighthouse keeper's dwelling took on a second life. A bird observatory opened inside it and is still running today, the second-oldest in Finland after Signilskär out in the Åland Sea, kept going by the Pori Ornithological Society. Autumn is the season that matters. Säppi lies far enough offshore that migrating birds funnel past it, and ringers work through the early hours while the weather does whatever it intends to do that week. Birdwatchers have made the island a fixture of the Finnish autumn, which is part of why roughly four thousand people a year make the crossing.

Every spring about fifteen Highland cattle are ferried out to graze. Shaggy and unhurried, they are working animals: conservation grazing keeps the shore meadows open for the plants and insects that depend on them, a job scythes did for centuries and nobody wants to do by hand now. The whole island sits inside the Luvian saaristo Natura 2000 area, holds nature reserves of its own, and part of it belongs to the Bothnian Sea National Park, established in early 2011 and composed almost entirely of water — around 98 per cent of its surface. The Finnish Heritage Agency has separately designated the lighthouse community and pilot station a built cultural environment of national significance, drawing the boundary around the entire island. Säppi belonged to Luvia's outer archipelago until that municipality merged into Eurajoki at the start of 2017.

In August 1997 someone walking the north shore found a dead dolphin. Not a porpoise — a common dolphin, Delphinus delphis, a male between five and seven years old, and only the second of its species ever recorded in Finnish waters. It emerged afterwards that a sea captain had seen the animal alive south of Säppi earlier that month, working its way up a cold brackish inland sea toward a coast where nothing about the salinity or the temperature made any sense for it. Säppi has that quality. Things arrive here with no business arriving, and the island quietly takes them in.