# List of islands of Wales

This is a list of islands of Wales, the mainland of which is part of Great Britain, as well as a table of the largest Welsh islands by area. The list includes tidal islands such as Sully Island but not locations such as Shell Island which, though they are termed islands, are peninsulas.
| Name | Island group/location |
| Anglesey (Ynys Môn) | Irish Sea |
| Bardsey Island (Ynys Enlli) | Gwynedd |
| Barry Island (Ynys y Barri) | Vale of Glamorgan (linked to the mainland during the 1880s) |
| Burry Holms | Gower |
| Caldey Island (Ynys Bŷr) | Pembrokeshire |
| Cardigan Island (Ynys Aberteifi) | Ceredigion |
| Carreg Onnen | Pembrokeshire |
| Carreg Rhoson | Pembrokeshire |
| Carreg yr Halen | Anglesey |
| Cei Ballast | Porthmadog (formed from ships ballast) |
| Church Island (Ynys Dysilio) | Anglesey |
| Cribinau (Ynys Cribinau) | Anglesey |
| Daufraich | Pembrokeshire |
| Denny Island (Ynys Denny) | Monmouthshire |
| East Mouse (Ynys Amlwch) | Anglesey |
| Emsger | Pembrokeshire |
| Flat Holm (Ynys Echni) | Bristol Channel |
| Gateholm | Pembrokeshire (tidal island) |
| Grassholm (Gwales/Ynys Gwales) | Pembrokeshire |
| Holy Island (Ynys Gybi) | Anglesey |
| Maen Gwenonwy | Llyn Peninsula (tidal island) |
| Middle Head | Gower (tidal island) |
| Middle Mouse (Ynys Badrig) | Anglesey |
| Middleholm (aka Midland Isle) | Pembrokeshire |
| Mumbles Head Island (Y Mwmbwls) | Gower (tidal island) |
| North Stack (Ynys Arw) | Anglesey |
| Puffin Island (Ynys Seiriol) | Anglesey |
| Ramsey Island (Ynys Dewi) | Pembrokeshire |
| St Catherine's Island (Ynys Catrin) | Pembrokeshire |
| St Margaret's Island (Ynys Farged) | Pembrokeshire |
| St Tudwal's Island East (Ynys Tudwal Fach) | St Tudwal's Islands |
| St Tudwal's Island West (Ynys Tudwal Fawr) | St Tudwal's Islands |
| Salt Island (Ynys yr Halen) | Anglesey |
| Sheep Island (Ynys y defaid) | Pembrokeshire (tidal island) |
| The Skerries (Ynysoedd y Moelrhoniaid) | Anglesey |
| Skokholm (Ynys Sgoc-holm) | Pembrokeshire |
| Skomer (Ynys Skomer) | Pembrokeshire |
| South Stack (Ynys Lawd) | Anglesey |
| Sully Island | Vale of Glamorgan (tidal island) |
| Thorn Island | Pembrokeshire |
| Tusker Rock (Ynys Twsgr) | Vale of Glamorgan |
| West Mouse (Maen y Bugail) | Anglesey |
| Worms Head (Pen Pyrod) | Gower (tidal island) |
| Ynys Benlas | Anglesey |
| Ynys Beri | Pembrokeshire |
| Ynys Cantwr | Pembrokeshire |
| Ynys Castell | Anglesey |
| Ynys Dulas | Anglesey |
| Ynys Eilun & Pont yr Eilun | Pembrokeshire |
| Ynys Faelog | Anglesey |
| Ynys Feurig | Anglesey |
| Ynys Gaint | Anglesey |
| Ynys Gifftan | Gwynedd (tidal island) |
| Ynys Gored Goch | Anglesey |
| Ynys Gwelltog | Pembrokeshire |
| Ynys Llanddwyn | Anglesey (tidal island) |
| Ynys Lochtyn | Ceredigion |
| Ynys Meicel | Pembrokeshire |
| Ynys Moelfre | Anglesey |
| Ynys Onnen | Pembrokeshire |
| Ynys Welltog | Anglesey |
| Ynys y Bîg | Anglesey |

## Largest islands in Wales

| | Island | Area (sq mi) | Area (km$^2$) |
| 1 | Anglesey | 260.37 | 674.36 |
| 2 | Holy Island | 15.22 | 39.44 |
| 3 | Skomer | 1.12 | 2.90 |
| 4 | Ramsey Island | 0.99 | 2.58 |
| 5 | Caldey Island | 0.84 | 2.18 |
| 6 | Bardsey Island | 0.79 | 2.06 |
| 7 | Skokholm | 0.41 | 1.06 |
| 8 | Flat Holm | 0.21 | 0.33 |
| 9 | Ynys Llanddwyn | 0.19 | 0.3 |
| 10 | Puffin Island | 0.11 | 0.28 |
| 11 | Cardigan Island | 0.06 | 0.15 |
* Holy Island and Anglesey are often counted together as they are separated by such a narrow channel.

## Inland islands

There are no islands of any great size in lakes in Wales. The crannog in Llangorse Lake is an artificial island. Several reservoirs contain islets e.g. Llyn Brenig, Elan Valley Reservoirs and Llyn Trawsfynydd, the last named having the largest and most numerous, though some are linked by causeways.

## Places called "island" or "ynys" that are not islands

Some places around the Welsh coast are called island or (Welsh) ynys, but are not. Caution is required in that whilst 'ynys' most commonly translates as island, it has other meanings too. Some of these named places were formerly islands surrounded by marshland. Others are peninsulas or just coastal settlements. They include:
* Barry Island (tidal island until the construction of Barry Docks in the 1880s)
* Berges Island, peninsula at Whitford Burrows, Gower
* Dinas Island, peninsula on Pembrokeshire coast
* Farchynys, locality beside Mawddach estuary, Bontddu, Gwynedd
* Little Island, peninsula at the west end of the former Barry Island
* Shell Island
* Traeth Mawr - there are multiple examples of names including 'ynys' around Traeth Mawr, the now drained estuarine flats of the Afon Glaslyn, Gwynedd, including Hir Ynys, Ynys y Gwely, Ynys Ceiliog, Ynys Fawr, Ynys-fach and Ynys Fer-las.
* Ynys, hamlet on an area of raised ground known as Ynys Llanfihangel-y-traethau at Morfa Harlech, Gwynedd
* Ynys and nearby Ynys-fach on coast south of Dinas Dinlle, Gwynedd
* Ynysboeth, area of Abercynon in the Cynon Valley, Mid Glamorgan
* Ynysddu, village in the Sirhowy valley, Caerphilly County Borough
* Ynyshir, village in the Rhondda, Mid Glamorgan
* Ynyslas, locality at Borth, north Ceredigion - there are multiple examples of names including 'ynys' around the Dovey estuary including Ynys Tachwedd, Ynysfergi, Ynys Greigiog, Ynys-hir, Ynys Edwin, Ynys-Eidiol and simple 'Ynys'.
* Ynys Leurad, a small peninsula near Four Mile Bridge, Anglesey
* Ynysmaerdy, village near Llantrisant, Rhondda Cynon Taf
* Ynyswen, village in the Rhondda, Mid Glamorgan
* Ynysybwl, village between the Rhondda and Cynon Valleys, Mid Glamorgan