Complex sentence: Portsmouth Mine Pit Lake, sometimes called the Portsmouth Pit, is the deepest lake in Minnesota at over 450 feet (137 m), according to the most recent Minnesota DNR data.
Split into simpler sentences: Portsmouth Mine Pit Lake, sometimes called the Portsmouth Pit, is the deepest lake completely within the state of Minnesota. It has a depth of over 450 feet (137 m), according to the most recent Minnesota DNR data.