Complex sentence: E. Lee Spence, a pioneer underwater archaeologist, was a longtime resident of Sullivan's Island and, in the 1960s and 1970s, discovered many shipwrecks along its shores.
Split into simpler sentences: E. Lee Spence, a pioneer underwater archaeologist, was a longtime resident of Sullivan's Island. In the 1960s and 1970s, he discovered many shipwrecks along its shores.