HOLLAND, MI (WOWO) Frigid temperatures and heavy snowfall have led to the formation of ice caves and ice volcanoes along Lake Michigan, with some structures reaching sizes not seen since the winter of 2014-15, according to Bridge Michigan. Officials warn the formations are unstable and advise anyone exploring the ice to stay well away from water edges, go with a partner, and carry a communication device.

Popular locations include Sleeping Bear Point in Leelanau County, Empire, Glen Haven, Leland, and Northport. Ice volcanoes form when waves push water through cracks in ice shelves, freezing into cone-shaped structures that can exceed 20 feet in height. Ice caves form as wave-sprayed water freezes along the shoreline, creating hollow formations.

Great Lakes ice coverage is rising this winter. Lake Erie is more than 95 percent frozen, Lake Huron over 77 percent, and Lake Michigan roughly one-third frozen, with additional frigid fronts expected to expand the ice, according to the US National Ice Center. Local officials describe this winter as among the coldest and snowiest in recent years.

“Stay well away from the water’s edge and explore with someone who has a device to call for help,” said James Schaberg, a local resident. “These formations are beautiful but unpredictable.”