Bwlc Islet is an artificial islet in Llangorse Lake, measuring about 42m by 29m. It was explored in 1868, and a survey and excavation carried out on and around the islet in 1989-92, demonstrated that the site had been occupied in the late 8th to early 9th century AD.

(Sources: Dumbleton 1870 (AC 4th series 1), 192-5; Campbell & Lane 1988 (AW 28), 67-8; 1989 (Antiquity 63), 675-81; Excavation & survey notices: AW 29 (1989), 57-8; AW 30 (1990), 62-3; AW 31 (1991), 38-9; AW 32 (1992), 77; AW 33 (1993), 36-7.)
J.Wiles, RCAHMW, 29.10.2004