They are known, simply, as hydrothermal vents. They only occur
in the deep ocean. Some specific types are cold seeps, white
smokers and hot smokers. If you are looking for specific
hydrothermal vents the Lost City and Loki's castle are fields of
hydrothermal vents in the mid-Atlantic and Majic Mountain is a
hydrothermal vent field located about 150 miles west of
Vancouver.