This is Romania's largest naturally dammed mountain lake, formed in 1837 at the foot of the "Hasmasu Mare" Mountaion, part of Hasmas National Park, in the Oriental Carpathians. Heavy rain caused rockslides that blocked 3 creeks in the area and the lake had been created since then by the accumulation of the water. With a 11 square km area and a maximum depth of 10 m, the lake sits at an altitude of 980 m in the mountain range. It is also close by The Bicaz Gorges, another surprising natural formation!
It is named after the reddish alluvia deposited by the Red Creek that made it exist, which runs rich in iron oxides and iron hydroxides. It is one of the country's most complex nature reserves. You can still see the tree trunks that once used to live on the area - now flooded, almost all underwater!