A survey revealed that Nun's Island was a complex stone structure with causeway-like features, while Castle Island showed the best potential, with a large assemblage of worked timbers. Two logboats were also recovered in 1968, one with dovetail joints. This work continues today. These Roman-period log-boats were constructed for lake fishing, and were about 8 m long, 1.5 m wide, and 80 centimetres deep, were made of oak, yew, and possibly willow. The boats were paddle propelled. Other notable constructional features are that they were complex boats: carved; dugout (extended); mortice-and-tenon; and sewn.