It has an area of some 36 hectares, and has been designated as a Site of Special Scientific Interest (SSSI) for its status as a nutrient rich lake with characteristic flora and fauna. The lake supports a good collection of reedbed birds and wildfowl, especially during the winter time, when it is possible to encounter coot, pochard and golden plover. There are wintering bittern – which have bred at the lake in the past, as well as greylag geese and oystercatcher.

One of the lake’s melodious summer visitors is the reed warbler – a bird which can often be heard singing from the dense reedbeds around the lake shore. Freshwater swan mussels are also known to occur. With regards to its plant life, Llyn Maelog supports eight species of pondweed, including the horned, perfoliate, blunt-leaved and lesser varieties. The shallow water margins harbour slender spike-rush and shoreweed and the reed swamp consists largely of common reed.

Yellow loosestrife also occurs, as does the locally uncommon greater spearwort. Lesser water-plantain and flowering-rush are other uncommon plants which occur within the lake margins. A public footpath circumnavigates the lake (except for the southernmost shore) and is linked to footpaths leading to Rhosneigr, and the area to the east around Llanfaelog. The Anglesey Coastal Path is accessible from a footpath to the south side of the lake, via a link which leads through the Tywyn y Llyn sand dunes. Llyn Maelog is unusual in the fact that it has ‘Village Green’ status. Designated as such in 2011, it is believed to be the only lake in Wales with such standing.