Seagrass in Llŷn: a nationally scarce sea flower

How perfect can you get? Porthdinllaen is a picture-postcard village, accessed by walking over a mile of sandy beach. The seagrass bed found here is one of the largest in North Wales and it forms part of the Pen Llyn a’r Sarnau Special Area of Conservation (SAC).


Seagrass beds are an incredibly important habitat. They support a wealth of biodiversity and provide important benefits, such as nursery areas for commercial fish species. They also help to absorb carbon dioxide, produce oxygen, cycle nutrients and filter pollutants.

Seagrass beds only occur in relatively clear and sheltered waters and therefore are only found at a few locations in the UK. At least 80% of the UK’s seagrass has been lost in the last century due to disease, poor water quality, coastal development and pollution, amongst other factors, and seagrass is now classified as nationally scarce.

Small but significant

Below the sea’s surface at Porthdinllaen, thousands of tiny creatures can be found hiding amongst this unique habitat. It's vital that we protect this special place without impacting on the current use of the area.

Sea flowers

Seagrasses are the only truly marine flowering plants in the UK. Three species occur in UK waters: common seagrass or eelgrass (Zostera marina), dwarf eelgrass (Z. noltii) and narrow-leafed seagrass (Z. angustifolia).

Why is seagrass important?

Seagrass beds are important marine habitats for a number of reasons. They are known to help stabilise the seabed sediments in addition to providing organic matter, shelter and food for a variety of fish, birds and invertebrates.

On a global scale they are also known to be significant sinks for carbon dioxide. The global value of all ecosystem services provided by seagrass beds is estimated to be worth trillions of US dollars.

Porthdinllaen: Plenty to do

There’s a lot to see and do at Porthdinllaen. It's a spectacular spot to enjoy a day on the coast with magnificent views, sheltered waters, fine sandy beaches, interesting rock pools, a chance to watch the comings and goings of local fishermen and the Ty Coch Inn on hand to provide refreshments.