Bull’s Porth is a remote bay at the northeast end of St Martin’s Isle, Scilly. It offers an anchorage in a remote and sequestered location.

The deep bay provides good shelter from east round through south to west. Attentive daylight navigation with good visibility is necessary to make any approach as outlying ledges need circumvention. It can be accessed at any stage of the tide, but the ideal time to enter is at half-tide or lower, when its primary hazard is visible.

Keyfacts for Bull's Porth

Position and approaches

Haven position

49° 57.954' N, 006° 16.578' W

This is on the 5-metre contour in the centre of the bay.

What is the initial fix?

This is on the charted alignment of Round Island Lighthouse, with Chad Carn (24 metres high on White Island) on 273.5°, to safely pass Deep Ledges. It is ½ mile northward of the bay.

What are the key points of the approach?

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What's the story here?

Bull’s Porth is a north-facing bay between Turfy Hill on the west and the Burnt Hill promontory to the east. It lies adjacent and close west to Bread and Cheese Cove, which is overlooked by St Martin’s daymark. Similar to Bread and Cheese Cove, the bay offers a well-protected deepwater anchorage but over a sandy bottom, and the cliffs at the back of Bull Cove are higher. A visiting boat will most likely have the cove to itself as this is very much off the beaten path in a remote and undeveloped part of the island.

How to get in?

Use southwestern England’s coastal overview from Land’s End to Isles of Scilly for regional approaches and Bread and Cheese Cove for final approaches.

When 400 metres north of Murr Rocks, it is safe to break off to starboard to pass between Santamana Ledges and Murr Rock. Located northward of Bull’s Porth and northeast of Turfy Hill Point, Santamana Ledges usually show as they dry to 4.9 metres. Keep centre, or east of centre, of the bay as it has rocky shores with some outliers on its western side.


Anchor according to draught and conditions. It is possible to land by tender on the stony beach of Bull’s Porth, in the southwest corner, but it is full of boulders. Other landing possibilities are the sandy beach of Bread and Cheese Cove to the east, or the long sandy expanse of Saint Martin’s Bay to the west. If the great sweep of sparkling white sand, arguably Scilly’s finest beach, proves too inviting to resist as an anchorage, Bull’s Porth provides the ideal stepping stone.




Great Bay requires some careful navigation between many rocky banks, and waiting for low water in Bull’s Porth allows its hazards to expose and be seen. The visible islands of the Mackerel Rocks (4.1 and 7 metres high) and Great Merrick Ledge (with islets 1 to 5 metres high set in an expanse of rock that dries to 3.9 metres) can always be seen. However, their surrounding ledges, along with the abovementioned Santamana Ledges (which cover and dry to 4.9 metres) and Little Ledge of Mackerel Rocks (drying to 3.6 metres) are better seen at low water. When it comes to anchoring, Great Bay has a mixture of sand, rock and weed from 2 to 5 metres, and is protected from southeast to south to west.

Why visit here?

The origin of the name Bull’s Porth is unknown. Porth in old Cornish means a bay, port or harbour, and perhaps the ‘Bull’ refers to the promontory headland of Burnt Hill, which it could be said to resemble. The headland is certainly historically significant, with human inhabitation stretching back a long way here.




Scilly has the remains of two confirmed Iron Age cliff castles – Giant’s Castle on St Mary’s, and Shipman Head on Bryher – while it is now believed that Burnt Hill was the site of a third. A recent review concluded that although the boulder wall across its neck did not constitute a rampart, there is ample other evidence of prehistoric activity to suggest it was a promontory fort. Remains of two low-lying roundhouses have been dated to the Iron Age, while lines of small standing stones protruding from the peat immediately outside the promontory between Bull’s Porth and Stony Porth would have demarcated the fort’s prehistoric fields. This all fits with the headland being a centre of occupation under a tribal chief, as hillforts have come to be seen today as nuclei for socio-economic development or ritual rather than defensive strongholds.




Although very difficult to securely date, it is likely that the ruins and field systems date back to the first millennium BC. The overall picture is one of an ancient village or settlement throughout this period. People from this time would live in oval or circular houses that would have lasted for centuries, farming the same small rectilinear fields, and using mainly stone tools with similar types of pottery. This lifestyle would have remained essentially unchanged throughout the early Iron Age, but changes would have occurred after 500 BC. From this time onwards, southwest-decorated (or Glastonbury) wares appeared, reflecting greater trading contact with the mainland. Caves on the north side of St Martin’s suggest there were ancient tin works here.


Since that time, the rugged weather-beaten northern slopes of St Martin’s, a ridge of granite exposed to all the fury of the Atlantic gales, have been left to their own to become the coastline that nature intended. Existing in secluded tranquillity, it is one of the widest and most remote in Scilly, almost entirely uncultivated and beautiful. Its crowning glory has to be the adjacent, unspoilt white sand beach of Great Bay. The ½-mile recess of sparkling white sand backed by grassy dunes ranks as one of the best beaches in Scilly, if not the UK, offering perfect bathing in its shallow turquoise waters. And it should be added that sparkling is no exaggeration here, as its sands are partly composed of tiny quartz particles that give it a pale golden colour and bring it alive in bright sunlight. Yet the magnificent bay scarcely sees more than a handful of families on its pristine sands, as most visitors opt for the instantly accessible southern beaches of Lawrence’s Bay and Par Beach.

Beyond Great Bay, a tidal causeway links the northwest of the island with lonely, uninhabited White Island, pronounced Wit-Island. It can be reached across the stony White Island Bar from its furthest tip, which covers only at high water. The tidal causeway, or isthmus, should be avoided when covered as strong currents run across it.

From a sailing point of view, Bull’s Porth, similar to Bread and Cheese Cove, is an important anchorage that provides shelter in the event of a southwesterly gale. The sea is that particular shade of turquoise blue and jade green peculiar to Scilly, which is highly attractive. It also provides a good staging point to anchor around Burnt Hill in the larger St Martin’s or Great Bay.

What facilities are available?

There are no facilities at this remote location.

With thanks to:

Michael Harpur, eOceanic.