Gvenderlaug is a landmark, 42°C miracle-producing pool (no bathing) that was blessed by the bishop Gvendur the Good in the 13th century and is now a national monument. The tiny, circular, rock-lined pool also feeds the outdoor pool and hot-pot at Hótel Laugarhóll. It's 50m along a trail that's signposted from the hotel's swimming pool changing rooms.