The ‘Dorn’ A silled lagoon on the eastern side of the Lough, and refers specifically to the channel which connects several exceptionally sheltered bays to the main area of the Lough. Rock barriers or sills hold back water as the tide falls, creating saltwater rapids, unique in Ireland. In the area of the Dorn rapids, abundant growths of sea anemones, sponges and ascidians clothe the rock and boulders. Several of the animals found in the area of the rapids normally occur in relatively deep water. The main trough of the Dorn supports a dense forest of sugar kelp Laminaria saccharina and sea-oak Halidrys siliquosa. The gravelly-sand bottom has unusually dense colonies of peacock worm Sabella pavonina and sand gaper Mya arenaria, with occasional native oysters Ostrea edulis and king scallops Pecten maximus. The channel enables sponges to grow to exceptional proportions. The sheltered marine ‘ponds’ feature beds of common eelgrass Zostera marina and the green alga Codium fragile ssp. tomentosoides.