St Helen’s Pool is located within the northern islands of the Isles of Scilly and to the south of the uninhabited island of St Helen’s. It offers an anchorage in a sequestered setting.

Unlike any other anchorage in the island group, St Helen’s Pool provides nearly all-round good shelter. Although having little in the way of air cover the surrounding islands and reefs that ring the anchorage keep it free of swell at all times save for at high tide. The approach requires careful pilotage and there is a moderately shallow inner bank that requires a sufficient rise of tide to cross to finally access the pool. Attentive daylight navigation in good visibility is therefore required to make any approach and preferably during settled or light offshore winds. It should never be attempted in strong winds with a big swell.

Keyfacts for St Helen's Pool

Position and approaches

Haven position

49° 58.056' N, 006° 19.463' W

This is in the centre of Saint Helen's Pool in about 7 metres LAT.

What is the initial fix?

This is 600 metres north-eastward of Round Island and on the charted Bab's Carn, a rocky bluff on the west side of St Martin's, with the Pednebean rock on 154° T alignment that is used to pass inside Deep Ledges, Tide Rock, Black Rock and Black Rock Ledges.

What are the key points of the approach?

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What's the story here?

St. Helen's is the third largest of the uninhabited islands in the Scilly archipelago. Comprising a total area of 20 hectares it is made up of a smooth 42 metre high rounded hill that is covered in grass and heather. St Helen's Pool is a spacious stretch of water lying close south of the island which provided a well-used anchorage for sailing ships in the past. Surrounded by islands and ledges it is virtually landlocked at low water whist at high water, it has a range of alternative entrances and exits that permitted sailing vessels of old to arrive or depart in most wind directions.

It remains an excellent leisure boat anchorage today with a unique property of enjoying near all-round protection. It is only somewhat exposed at high water when the tide overtops its surrounding ledges but the vast majority of any waves have already been broken up and only some swell remains, particularly form the northwest or south. It is an ideal anchorage for larger boats who are less subject to the swell who want to avoid constantly moving to find protection against wind shifts.

How to get in?

At high water, there are several alternative approaches to permit access from St Mary’s Road and Old Grimsby Sound. Much of the area between Tresco, Tean and St Martin’s uncovers at LAT but the principal small boat channels only dry to 1 metre at their shallowest. So, with MHWS being 5.7m and MHWN 4.3m, high water provides ample depth for leisure craft to move freely about. Pilotage through the channels however requires some care and should only be attempted, on a first visit, with the benefit of a rising tide. Seaward entry into St Helen’s pool is via St Helen’s Gap that is located between St Helen’s and Tean. It is largely seen as the easiest approach and we describe this here.




Unmarked and running in between two flanking rocky ledges Helen’s Gap may look thoroughly uninviting on the chart but it is deep and readily navigable in daylight during moderate conditions. Helen’s Gap and Tean Sound are the two most frequently used passages from the north into the main anchorages to the west of St Martin's.




However, unlike Tean Sound, Helen’s Gap has an inner shallow bank between it and the Pool of 0.5 metres LAT that requires a sufficient height of tide to provide clearance. This cannot be crossed at LWS but it being only moderately shallow it should be available to cross more often than not be by leisure vessels.

The seaward approaches may be positively identified by Round Island and its prominent all-white lighthouse, Fl.10s55m18M, that provides an excellent daymark for the north end of the archipelago. There is also plenty of sea room in the approaches and entrance.




Use southwestern England’s coastal overview from Land's End to Isles of Scilly for local approaches. Vessels approaching from the east should keep north of a latitude of 49 59.000 N to clear White Island, Lion Rock and Deep Ledges. Vessels approaching from the west or north, keep up towards Round Island, taking care to avoid the Eastward Ledge, drying to 2.9 metres, located 150 metres to the northeastward of the island.




From the Bab’s Carn initial fix, located 600 metres northeastward of Round Island, steer southward to pass midway between Saint Helen’s prominently rocky easternmost extremity of Didley’s Point and Pollard Rock that dries to 1.7 metres.

The gap between Round Island and Eastward Ledge and Deep Ledges, Tide Rock, Black Rock and Black Rock Ledges, passed to port in succession, is more than a ⅓ of a mile wide. Maintain a careful watch nevertheless as the tide runs strongly across the approach.




The gap between Didley’s Point and Pollard Rock is about 300 metres. However Pollard Rock will most likely be covered, but the midway point is about 150 metres eastward of Didley’s Point on the 10-metre contour.




From here the 2.3 metres high East Gap, to port, and 0.9 metres West Gap, to starboard, rocks, will clearly be visible. Situated at its narrowest part The Gap Rocks they are like a pair of entrance gateposts to Saint Helen’s Gap. They stand close to the edges of their respective reefs, at about 100 metres from ledge to ledge, and there is at least 3 metres at low water springs midchannel. Steer towards West Gap Rock until about 100 metres off, to avoid a rocky ledge that extends about 50 metres northwest from East Gap Rock, then turn to pass just to the West Gap Rock side of centre.




Continue south by southwest for 250 metres resisting the temptation to turn towards vessels already moored in Saint Helen’s Pool. A drying sand spit extends more than 300 metres southeastward from the island shore adjoining the West Gap reef which should be visible.




After 250 metres the edge of the inner shallow bank laying between Old Man and St Helen's should be reached. Check the tidal height to ensure you have enough clearance to pass over the charted LAT of 0.5 metres before proceeding. With a sufficient rise, steer south-westward to cross the final 300 metres tat lead into the centre of St Helen’s Pool where 7 metres LAT will be found.




Anchor according to conditions in sand good holding from 2m to 7m of water. There is ample deep water in the main pool. Keep clear of the area to the southeast of St Helen's Island as it dries out to West Rock dries with a sandy spit, drying to 2.9 metres, that hooks round to the south and west from the island. A deepwater section extends a ½ mile south-eastward from 150 metres off the southern end of Saint Helen’s Island to the distinctive 14 metres high Hedge Rock islet.




Land by tender on the island which is uninhabited and has no resources. Alternatively, the neighbouring Old Grimsby Harbour, on Tresco, and St Martin’s Tean Sound are a ½ mile dinghy run for further exploration and facilities.

Why visit here?

Known in Cornish as Enys Elidius and like many of the religious names for the group St Helen’s most likely got its name from its long history of hermits and monks. The monk in question was the Cornish hermit monk saint Lide, also known as Elid, Elida, Elide, Lyda, Lyde and more regularly Elidius which is most likely a Latinization of the saint's original Cornish name. The English name is a religious corruption of the Cornish saint's name.




It has the remains of the oldest Christian sites in Scilly, probably founded during the 8th to 10th Century, that is thought to be his heritage it is known as St Elidius Hermitage. The remains can be seen on the southern slope of the island today and comprise a small complex that includes a circular living cell. The site developed from that of a solitary hermit site believed to belong to Elidius' original dwelling, with a single round hut and oratory. Reputedly a bishop also the son of a king he was renown for his psychic powers and ability to foresee the future. During his time here St Elidius he is believed to have converted the Viking King Olaf Trygvasson of Norway to Christianity in 988, see New Grimsby, when he came to raid the islands.




Later his dwelling had increased in importance to be converted into a simple chapel and over time it spread out to be a communal hermitage with a number of rectangular huts for individual accommodation, surrounding the church and oratory buildings. In the early 11th-century, a small early Christian chapel named St Elidius was built on the northeast side of the island and was granted to Tavistock Abbey around 1120 AD. This increased the numbers of pilgrims visiting the burial site of Elidius and it is said that there was once a causeway from Tresco's Abbey Church across the downs to the small church on St Helen's. During the late medieval period, St Helen's Pool was considered the main harbour of the island group. Off Old Grimsby, with good holding ground, reasonable depth of water the possibility to depart or access from many points and excellent sheltered from the prevailing south-westerlies. There is even evidence to suggest that the monks of Tresco may have collected mooring fees from ships anchoring in St Helen's Pool. It was here that Admiral Blake took his fleet when retaking the islands at the end of the civil war.

Nearby the site of St Elidius Hermitage are the melancholy ruins of the Pest House. At that time Scilly was a major port of call for sailing vessels and St Helen's Pool was by then an alternative anchorage to St Mary's. In 1756 law stated that any plague-ridden ship England bound and north of Cape Finisterre would have to abandon any of its passengers or crew who showed signs of any contagion in Old Grimsby. The authorities would have been very keen to avoid having infectious patients anywhere near the group's principal harbour and settlement on St Mary's and in 1764 St Helen's replaced Old Grimsby as the plague quarantine station. The Pest House was constructed then as a place to treat infectious patients, especially cholera victims, who had previously been abandoned to their fate. The interior is of a single ward with two other rooms, the surgeons quarters and treatment rooms on the eastern end. The station included the building of an isolation hospital as well as a slipway and quay on the south side of the island.

Few people recovered because the sufferers of even harmless disorders, such as rosacea, acne, had to share bedstraw with people suffering seriously contagious diseases such as bubonic plague or cholera. The associated graveyard includes passengers from Africa and Asia who died at the station. In Old Town Church there is the gravestone of a Lt James Allen Corsse a naval surgeon sent to treat the sick. He died of cholera within a week at the age of 27. Later, in more happier times, the commander of a guardship moored at St Helen's Pool during the Napoleonic Wars made a garden on the island. Mesembryanthemum, characterized by long-lasting flower heads, and the ground-creeping plant with succulent leaves Hottentot-fig escaped and naturalised. Some deer and goats were placed upon the island and can be occasionally seen.




Today the island is the major part of St Helen's, inclusive of Northwethel and Men-a-vaur, Site of Special Scientific Interest and is designated for its rare flora and breeding seabirds. Some of its features have been given the designation of scheduled ancient monuments and it is currently managed by the Isles of Scilly Wildlife Trust. The remains of Pest House's granite quay can be seen alongside the sandy beach bay. The slipway to land the patients and stores, a quarter of a millennium later, has remained clear of rocks. The ruined pest house is just behind the dunes. Its massive granite walls and red brick chimney have stood the test of time in its exposed position. It has recently been repaired and stabilized to prevent its collapse with the help of English Heritage funding. The early medieval religious complex can be seen nearby. Open-air services are still held here once a year during August for Elidius and he is the patron saint of the Isles of Scilly.




From a boating perspective, St Helens Pool's surrounding formidable reefs provide wonderfully protected from the Atlantic swell rolling in from the west. Here, throughout most of the tide, perfect tranquillity can be enjoyed whilst listening to the thunder of breaking surf on Golden Ball and Golden Ball Brow to the northwest. It is a picturesque expanse of water, crystal clear and aquamarine when the sun comes out, with verdant islands or spectacular rocky outcrops all round. What it offers most is solitude without the need to constantly be prepared to move in the event of a wind shift. For those in the possession of a stalwart engine, there are countless fine sandy beaches all round with uninhabited and inhabited islands to explore.

What facilities are available?

The uninhabited island has no resources whatsoever. However, neighbouring Old Grimsby Harbour, on Tresco, and St Martin’s Tean Sound are a ½ mile dinghy run.

With thanks to:

Michael Harpur, eOceanic.

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