Carl Lowenstein (1934 – November 16, 2015) was an American physicist and oceanographer who participated in early deep‑sea exploration projects, including the 1980s search for the RMS Titanic. Born in New York City, he earned a B.S. from Kent State University and a Ph.D. in Applied Physics from Harvard University in 1963. He joined the Marine Physical Laboratory at Scripps Institution of Oceanography in 1964, where he worked with towed sonar instruments for seafloor mapping and locating manganese nodules. Lowenstein was also known for his passion for computers, slide rules, and puzzles, and enjoyed traveling and camping with his family. He and his wife Claudia were married for 50 years; he is survived by her, their three children, two grandsons, and three great-grandchildren.