Britain’s largest islands

Disclaimer: please note that due to the Covid-19 pandemic, the poster is temporarily unavailable.

UPDATE – buy the poster here: https://onlineshop.shef.ac.uk/product-catalogue/professional-services/university-gifts-souvenirs/great-britains-islands-poster

Great Britain is an island in its own right, but aside from the mainland, there are hundreds of islands around the British coast, many uninhabited*. Inspired by David Garcia’s data visualisation of the Philippines, our GeoDataViz team worked with Alasdair Rae at the University of Sheffield to explore Britain’s largest islands.

They found that there are 82 English, Scottish and Welsh islands larger than 5km2. Scotland boasts the vast majority with 71, not surprising when you consider the Outer Hebrides, Shetland and Orkney and other beautiful islands off the coast. Wales had just 2 entries and England 9.

The team used Boundary-Line to define the area and length of coastline for each island, with some interesting results. While Lewis and Harris topped the tables for being the largest island by area and boasted the longest coastline, not all islands had such a correlation. North Uist (shown below) was the twelfth largest island, but has the fifth longest coastline. Conversely, Arran was the eighth largest island but has the eighteenth longest coastline.

Adding in data from AddressBase, the GeoDataViz team compiled the number of residential addresses on each island and quickly realised that having the largest area does not equate to having the most addresses. Mull is the fourth largest island, but eighteenth when you look at addresses. Portsea Island tops the table for most residential addresses, but is 38th in the list of islands be area.

How we created the visualisation of Britain’s islands

To create the beautiful islands poster, our GeoDataViz team loaded the data into a PostGIS database. From here, they could analyse the data to calculate island area, coastline length and residential address counts. Once completed, they imported the data to QGIS, where we applied colour schemes (we used our GeoDataViz Toolkit for this) and other styling elements. Each island was exported separately and then imported into Adobe Photoshop to produce the poster layout and apply the final touches.

Alasdair complemented this with a gif to showcase more of the islands’ data. Alasdair has been a keen user and sharer of our data since the OS OpenData portal went live in April 2010. He formerly led the MSc in Applied GIS at the University of Sheffield, of which Joe Harrison (the poster designer) is a recent graduate, and has a longstanding interest in geovisualisation so he was an ideal person to collaborate with on this project.

Test your knowledge of Britain’s largest islands

Try out our quiz and see how well you know the islands off the mainland. You can share your score with us on Twitter.

Facts and figures

Top 5 islands by area

  1. Lewis and Harris
  2. Skye
  3. Mainland, Shetland
  4. Mull
  5. Anglesey

Top 5 islands by length of coastline

  1. Lewis and Harris
  2. Mainland, Shetland
  3. Skye
  4. Mull
  5. North Uist

Top 5 islands by residential addresses

  1. Portsea Island
  2. Isle of Wight
  3. Anglesey
  4. Isle of Sheppey
  5. Canvey Island

Find out more

If you’d like to look at the islands’ graphic in more detail, you can download it from our Flickr page.

You can also download the full list of statistics here.

* Note we are looking at Great Britain’s islands, so this doesn’t include Northern Ireland’s islands, the Isle of Man or the Channel Islands. You can see more about the difference between Great Britain, the United Kingdom and our Crown Dependencies in this blog.

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50 Responses

          1. Jocelyn

            Jon, glad to hear you’ve found the Flickr page. Please note that due to the Covid-19 pandemic, the poster is temporarily unavailable and this is why you’re getting the 404 page. When this changes, we will update the first line of the blog to reflect this. Many thanks, Jocelyn

    1. Hi Ian

      You can download and print them at home in sizes A0-A4. The link to our Flickr channel is at the bottom of the blog.

      Thanks, Gemma

      1. Sharon Halliday

        Hi Gemma, Could you add a link to the OS flickr page as i cant see a link to it on your blog and I also cant find it searching on flickr :/


  1. Steve

    The link above to the table of statistics for the islands which are on the list is useful. Is it possible to obtain area data for all of the islands that the GeoDataViz team mapped? I assume they must have had a longer list of candidates, some of which turned out to be smaller than 5km-squared.

    1. I’m afraid they set the parameters for their search Steve and we haven’t pulled data on all islands of all sizes. It also comes down to that tricky question of when does an island stop being an island and become a piece of rock!

  2. Glennis Rogerson

    I copied it but the printing is blurred. Can I buy a copy and where from and price please. I am in the UK.

    1. Hi Glennis, there’s a link to our Flickr page towards the bottom of the blog and you can download and print at various sizes there

  3. Imelda McFaul

    Hi, is it possible to get a ‘poster style’ copy of the mapping image for my boy’s room? Or a quailty image that could be replicated. He is big into geography and as we live on an island, whilst not included on this map he would love it!! (Me too by the way). If not, no harm done. Thanks.

    1. If you click on the link to our Flickr page towards the end of the blog, you can download and print copies at various sizes Imelda

  4. Dave

    This is all great stuff…I’m confused by the figures for Holy Island (Lindisfarne?)
    Current pop c.180 yet you list 7400 Residential addresses and its area seems way inflated too….
    Think I must have the wrong island??

    1. Hi Dave

      Yes, the Holy Island here is the island off Anglesey in Wales. There are Holy Islands off England, Scotland and Wales as it happens!

      Thanks, Gemma

  5. Cheryl Hand

    This is brilliant!
    So much easier to see & find the various islands than scattered around a map of the UK.
    This would be a definite money generator if it was sold in poster size.
    Would love one framed & displayed in pride of place in my Australian home….
    Well done!

  6. Richard Hallam

    Pleeeese just make these available for purchase. The download isn’t as straightforward to many as you like to suggest. I then have to go a ‘debate’ the copyright issue with Office Max before they refuse to print it off. Just make sakeble copies that people can buy. Please!

    1. Hi Sheila

      It’s because it’s permanently attached to Hoy via a causeway, it’s the same situation for the Isle of Portland in Dorset too.

      Many thanks

      1. Kevin Burden

        I don’t think that can be the reason – the causeway crosses a bridge (Ferry Bridge) over a short but continously flooded stretch of tidal water (the Fleet). In this respect it’s no different, I believe, to Canvey Island or Hayling Island.

        There is another land bridge, the 11-mile shingle ridge known as Chisel Beach. I think that it is this which geographically speaking ties Portland to the mainland, making it a tombolo or spit-tied island.

        Given that it is very difficult indeed to walk this distance on large pebbles, Portland developed like any other inshore island, and that is reflected in its title as the Isle and Royal Manor of Portland. It is logical, but rather arcane, to exclude it from a list of Britain’s islands.

  7. Sarah

    Hi, do you know if it’s possible to buy a print or get a jpeg of the image used on this page – Great Britain’s Islands larger than 5km ?
    Many thanks

  8. Pingback : my small blog ~039 The truth? Dream on | Mark Goldthorpe

  9. Nick

    Hi Gemma,

    I have just received a print of this map as a delightful birthday present. I’m thinking of printing the correspondence above alongside it as an example of the perils of nationalism and ‘border’ thinking on this small planet that we all inhabit. I’d echo the nice points made in the Mark Goldthorpe blog link above.

    But having said that 🙂 ….. WHAT ABOUT THE SCILLIES? An archipelago off Cornwall, mostly owned by the Duchy of Cornwall and administered as a County Council in Cornwall. I don’t really see why the Isles of Scilly are out and the Isle of Wight, Portsea, Canvey etc are in. St Mary’s is big enough to count in your list, at 6.58 square kilometres (2.54 sq mi)

    I do hope it’s not an error…. I’d find a technical explanation more entertaining!

    Is it that they are too far? Having spent spent 12hrs and 70+ miles sailing back in from them this summer in a (lovely) old boat in bad weather I could understand that!

    Apologies for any nerdiness…. 🙂

  10. Nick

    Isles of Scilly – Archipelago – like the Hebrides, Orkneys and Shetland
    St Mary’s: 6.58 square kilometres (2.54 sq mi)


    (apologies if duplicate post)

    1. Hi Keith

      So, in terms of area, it would meet the poster criteria, but in terms of how we have defined an island, it doesn’t. There are mud flats and marshland classified in our database which keep Scolt Head Island ‘attached’ to the mainland. So by the methodology the team used for islands to qualify for the poster, if something was attached to the mainland, even by wetlands, it didn’t qualify.

      Many thanks

  11. Pete

    Hi Gemma
    Fantastic work and detail! As a former resident of the area, I have to mention that the eastern-most point of Great Britain is actually on an island. The towns of Lowestoft and Gorleston are on the island of Lothingland created by the tidal rivers Waveney and Yare and a cut linking the Waveney to Oulton Broad in the south. It is only connected to the mainland by a handful of bridges and the encircling water is tidal. Should this be considered for the list?

    1. Hi Hugh

      Good spot – we’re mortified. We’re also amazed that nobody else has pointed out our error in the last 12 months. We’ll get this updated.

      Many thanks

  12. Neil Cunningham

    Please can you tell me where St. Mary’s is?The image on the poster does not look like the St Mary’s on Google maps?

      1. Neil Cunningham

        Hi Gemma,

        I see that now thank you – that is in the Isles of Scilly.

        I have been to 68 of the islands now only 14 to go!

        thanks for a great project!

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