This national park is renowned for the perfectly round, pristine turquoise lake (220m deep) for which it was named. Overnight visitors can use the cooking facilities, so come prepared with food and drink. There is only one shower. You can no longer rent canoes for exploring the lake, but there are about 4km of interpretative trails to explore.
Until recently, this Guatemalan gem was rarely visited by travelers because it was an active, violent area during the civil war and the road was in disrepair. Now it fills up quickly on weekends and public holidays, and if you're thinking about coming at these times, it's a good idea to call and reserve a space.