The Eastern Isles () are a group of 12 small uninhabited islands within the Isles of Scilly Area of Outstanding Natural Beauty, part of the Scilly Heritage Coast and a Site of Special Scientific Interest (SSSI) first designated in 1971 for its flora and fauna. They have a long period of occupation from the Bronze Age with cairns and entrance graves through to Iron Age field systems and a Roman shrine on Nornour. Before the 19th century, the islands were known by their Cornish name, which had also become the name of the largest island in the group after the submergence of the connecting lands.Weatherhill, Craig, Place Names in Cornwall and Scilly, Wessex Books, 2005
All of the land designated as Eastern Isles Site of Special Scientific Interest is owned by the Duchy of Cornwall.
Geography The islands are located to the south-east of St Martin's and are within the Isles of Scilly Area of Outstanding Natural Beauty and part of the Scilly Heritage Coast.
The Isles are not so exposed to gales as the Western Rocks; consequently, the soils do not receive so much salt spray, and remnant habitats such as coastal grassland and maritime heath have survived the inundation of the sea. If the practice of summer grazing had continued, there would be even more grassland instead of the dense bramble that has smothered some of the small growing plants.
The islands by area are: Great Ganilly Great, Middle, and Little Arthur Menawethan Little Ganilly Great Innisvouls Great Ganinick Nornour Little Ganinick Little Innisvouls Ragged Island Guther's Hanjague
Geology The underlying rock is coarse-grained Hercynian granite topped by wind-blown sand. Some of the islands are linked with boulder ridges and sandy bars; at low tide, they can appear to be one island. During the Roman occupation of England and Wales, the area was a low-lying plain between St Mary's and St Martins and the present Eastern Isles small hills. The Isles of Scilly are a Geological Conservation Review (GCR) site for the largest assemblage of tied islands outside of Orkney and Shetland. Four islands represent the different stages in the linkage of islands by a sandy bar or tombola: Teän (not part of the Eastern Isles) to the north-west, between St Martin's and Tresco; and Great Arthur, Great Ganinick, and Little Ganinick to the south-east of St Martin's.
Wildlife and ecology Most of the islands have dense cover of bramble (Rubus fruticosus) and bracken (Pteridium aquilinum) as well as grassland along the coastal fringes. Goldenrod (Solidago virgaurea) is locally abundant amongst the heath communities growing on the podzolic soils on the higher parts of the islands. The heaths are classified as a poor fit somewhere between H10 and H11; the heather (Calluna vulgaris), bell heather (Erica cinerea), and bracken merge into pure bracken on the lower slopes. A feasibility study is needed to decide if the vegetation would benefit from grazing through a Higher Level Stewardship (HLS) agreement. Because no botanist resides on the Isles, and recording plant species on remote islands is difficult, there have been few botanical surveys. The number of species for each of the Eastern Isles was finally published in 1971, based on surveys carried out by J.D. Grose, Mr & Mrs J.E. Dallas, and J.E. Lousley in 1938 and 1939. Lousley listed 111 species of higher plants in his 1971 Flora, and by 1999 further surveys recorded a similar number (114). Some of the islands have species found only on the island in question and not on the other Eastern Isles, such as an oak tree found by Mr and Mrs Dallas on Great Gannick. Possible ancient woodland indicators such as butcher's-broom (Ruscus aculeatus), wood spurge (Euphorbia amygdaloides), and wood small-reed (Calamagrostis epigejos) have also been recorded on Great Gannick. The nationally rare orange bird's-foot (Ornithopus pinnatus) is found on the northern side of Great Ganilly.
The Eastern Isles are one of three main grey seal (Halichoerus grypus) pupping areas, the Western Rocks and Norrard Rocks being the others. Four other mammals have been recorded: rabbit, brown rat (described as a plague on some of the Eastern Isles,) house mouse, and the so-called Scilly shrew.
The isles are also home to breeding colonies of eight species of seabird, including three species of gull, as well as the common shag (Phalacrocorax aristotelis), great cormorant (Phalacrocorax carbo), northern fulmar (Fulmarus glacialis), razorbill (Alca torda), and puffin (Fratercula arctica). Several of the isles are closed to visitors during the birds' breeding season (15 April to 20 August).
The islands
Great Ganilly
Great Ganilly () (), is the largest of the Eastern Isles and consists of two hills joined by a low sandy neck. The hill further to the north has the highest point at and a ruined Bronze Age entrance grave on the summit. Stones from the chamber have been used to make a pyramidal navigational marker. Other evidence of past occupation include a hut circle on the neck as well as the remains of field systems. A freshwater spring would have made living possible on the island during the kelp burning season. The hills have maritime heath on each summit and dense bracken communities on the lower slopes. The surveys of 1938 and 1939 recorded a total of 74 plant species, the largest number on any of the Eastern Isles, including Portland spurge (Euphorbia portlandica), sea spurge (Euphorbia paralias), sea-kale (Crambe maritima), and balm-leaved figwort (Scrophularia scorodonia) in the small sand dune system. Common thyme (Thymus vulgaris) and orange bird's-foot grow on the heath, which is dominated by bell heather. Betony (Stachys officinalis), a common plant in Cornwall but known to be in only two places in Scilly, was discovered simultaneously here and on Tresco in 1998 but was not seen in 2000. Mammals recorded are the rabbit, brown rat, house mouse, and Scilly shrew.
Great, Middle, and Little Arthur The Arthurs (), part of the Geological Conservation Review site (GCR), are three rocky islands joined by two beaches forming a crescent around Arthur Porth; compare with Great Ganinick and Little Ganinick (see below) where the process is ongoing. Great Arthur (), as the name suggests, is the largest; it has a fringe of maritime grassland, dune vegetation, and strandline vegetation. There are three entrance graves on the summit ridge connected by a prehistoric boulder wall and surrounded by maritime heath with English stonecrop (Sedum anglicum) on the bare areas. The area of blown sand is dominated by marram grass (Ammophila arenaria), which helps stabilise the dunes and shelter a relatively rich flora of non-maritime plants such as stunted grey sallow (Salix cinerea). This (probably the same) plant is recorded in both Louseley (1971) and Parslow (1997).
Middle Arthur () has an unusual boat-shaped entrance grave on the summit with walls of standing slabs. A ceramic burial urn together with pieces of bone and flint were found during excavations in 1953. The island has a few patches of heather and some strandline vegetation in the sheltered areas of its shore; Little Arthur () has bracken on the deeper soils, heath on the summit, and English stonecrop in the bare areas. Also on Little Arthur is a small area of strandline vegetation and sand dunes with slender St John's-wort (Hypericum pulchrum), a plant common in Cornwall but uncommon in the Isles of Scilly.
Menawethan Menawethan () () is a steep-sided island to the south-east of the group with vegetation that is typical of islands with breeding seabirds. It was one of the first islands where Natural England carried out rat eradication. Some areas are covered in hottentot fig (Carpobrotus edulis; probably carried to the island by gulls); thrift (Armeria) and sea campion (Silene uniflora) also dominate in some areas. Other species recorded include Yorkshire fog (Holcus lanatus), orache (Atriplex), common scurvy-grass (Cochlearia officinalis), and tree-mallow (Malva assurgentiflora), which forms temporary stands in some years. Brookweed (Samolus valerandi), a plant restricted to cliff flushes in Cornwall and an unusual plant in Scilly, grows among rocks above the shore. The rocky shore is used by grey seals for haul-outs. A Bronze Age cairn stands on the summit. The island is recorded as Mynangwython c. 1588.
A cargo ship for the Isles of Scilly Steamship Company, due to enter service in 2026, has been named after the island.New Isles of Scilly freight ship is launched BBC News 4 November 2025Scilly Ferries Ships Monthly January 2026 page 10
Little Ganilly Little Ganilly () () is just to the north of Little Arthur and has a small area of heath on the summit. Bracken dominates the slopes, and there are maritime grassland and cliff communities along the coast, which has several small caves on the east side. Surveys in 1938 and 1939 recorded 37 species of plants. The only mammals recorded are brown rats and grey seals, the latter of which use the island for haul-outs.
Great Innisvouls and Little Innisvouls Great Innisvouls (, great wether island) (), has a small area of maritime grassland and bracken, and Little Innisvouls (, little wether island) () has strandline plant species. Both have breeding seabirds, and the Scilly shrew has been recorded on Great Innisvouls. Gurney reported 12 pairs of European shag (Gulosus aristotelis) with egg and one pair with young on Great Innisvouls on 12 May 1887.
To the north-east of Little Innisvouls is a small rock called Mouls () (), where a nationally scarce pseudoscorpion (Neobisium maritimum) was found in 1927.
Great Ganinick and Little Ganinick
The islands of Great Ganinick and Little Ganinick (, place of wild garlic) (), are part of the GCR and are in an early stage of the linkage of two islands by a tombola. The sand bar is building northwards from Little Ganinick towards the larger island, although the sand supply does not appear to be sufficient to link the two islands. On the north side of Great Ganinick, a cuspate-shaped beach is forming. Great Ganinick has the only known oak tree in the Eastern Islands. Described by Mr and Mrs Dallas in 1938 as ".... about 2 ft 6in (0.76 m) tall in tangle of bracken, bramble, and honeysuckle" (Lonicera), the tree (or possibly one like it) was still there in 1997. Great Ganinick is rich in plant species; Lousley recorded 74 species, including butcher's-broom, wood spurge, wood small-reed (Calamagrostis epigejos), and white ramping fumitory (Fumaria capreolata). Little Ganinick has grassland with strandline vegetation and seabird colonies.
Nornour