Bardsey Island is just 1.5 miles in length and, at its widest point, it is just over half a mile across. The mountain, Mynydd Enlli, rises to a height of 167m. It covers an area of 180 hectares, most of which is farmed.

The island was bought by the Bardsey Island Trust in 1979 and is managed by the Trust in and is a National Nature Reserve, Site of Special Scientific Interest and part of the Llyn Environmentally Sensitive Area. It is a site which is both nationally and internationally important for wildlife. The wide range of special interest includes birds, rare flowering plants, lichens, liverworts and mosses, coastal grassland and heathland, seacliff ledges and marine wildlife. It forms part of several larger sites around the mainland coast and seas of the Llyn Peninsula which are recognised internationally for their outstanding wildlife, in particular their birdlife, seacliff habitats and marine wildlife.

Day trips usually start from Porth Meudwy and as a general rule you should set aside a good 4 hours to explore the Island. Free range eggs and freshly grown vegetables are available throughout the summer from the Island farm. The farm cafe is open daily and serves tea and coffee. There is also a selection of cold drinks and flapjacks/biscuits for sale in the shop. The Craft shop is open throughout the summer, selling Island made crafts such as baskets, felt items, hand knitted hats and gloves, wool rugs, enamels, jewellery and a selection of cards. Honey from the island bees is also on sale. Bardsey truly is a unique and beautiful island to visit.