The marine Ikka Fjord in Greenland is well known for its remarkable submarine columns made of the cold-carbonate ikaite (CaCO₃·6H₂O). Here, natural processes lead to fast-precipitating ikaite at low temperatures (< 10°C) when carbonate-bearing groundwater seeps through fractures in Ikka Fjord and mixes with seawater. Within an area of 0.75 km², 678 columns of 1 - 20 meters height have been registered, continuously growing at rates measured at 50 cm per year. Understanding this natural system is of importance for carbon capture and storage efforts as it represents a very efficient method for carbon mineral storage in cold seawater.