An ice circle is a thin, circular slab of ice that form in slow moving, rotating part of a river. They are natural phenomena that are rare, but certainly not unheard of. Similar features are ice discs, ice crepes, and ice pans. They can vary in size up to more than 15 m (49 ft), with a maximum observed of 91 m (298 ft) on the Presumpscot River in the state of Maine (USA) this month (January 2019, Figures 1, 2, and 3). The slow-moving water freezes faster water rotating water around it, forming a circle of ice. They are generally a loose conglomeration of small chunks of ice. Videos of the Presumpscot River ice circle are available on Vimeo and YouTube.