The island is a procession of prominent hills all joined to one another by low-lying necks and sandy bars. It would only need sea levels to rise by a few metres for the southern part of Bryher to transform itself into a group of five or six separate islands. As all these hills – Gweal, Timmy's, Watch, Heathy and Samson – are exposed and windswept. Watch Hill, the island's highest point, has a stone marker on top and small stone shelter that was possibly once used as a look-out by gig crews watching for wrecks. The island has a length of , a maximum width of and an area of , including Shipman Head, which rises to at the northern end of the island. Bryher lies to the west of
Tresco, and is separated from that island by the Tresco Channel, once the main anchorage for the islands and now an area where sandflats are exposed at low tide. Off the southern end of Bryher is the uninhabited island of
Samson. It is possible to walk between the three islands at the lowest
spring tides. The settlement at the Pool is the westernmost in England. Without the
tidal island of
Gugh included,
St Agnes is marginally smaller than Bryher; however if Gugh is included with St Agnes, which is the common interpretation, then Bryher is (again, marginally) the smallest of the populated isles of Scilly. ; on Rushy Bay Green, Bryher. The centre of Bryher is mainly low-lying with arable fields, pasture and housing and is where most of the population live. On the west side is the
brackish Great Pool - the only true brackish lagoon on Scilly - which is separated from the sea by a narrow storm beach, and in the south are sandy beaches like Rushy Bay. The island lies within the Isles of Scilly
Heritage Coast, is part of the Isles of Scilly
Area of Outstanding Natural Beauty and untenanted land is leased by the
Duchy of Cornwall to the
Isles of Scilly Wildlife Trust which is using ponies and
red ruby cattle to graze the overgrown areas as part of the
Waves of Heath project.
Hell Bay The infamous Hell Bay, named for its wild waves and swell, is on the north-west coast of Bryher, immediately to the south of Shipman Head. This
Atlantic-facing cove became a notorious place for
shipwrecks in the 18th and 19th centuries, although most ships wrecked on Scilly were wrecked on the many hazards in the Western approaches to the archipelago well before they could reach Hell Bay. Hell Bay also gives its name to Bryher's only hotel, Hell Bay Hotel, which is the most westerly hotel in England. ==Civil parish and ward==