[3][4] McCann began scuba diving in the early 1960s with Jacques Cousteau, exploring ancient Roman shipwrecks near Marseille.

"[5] Between 1961 and 1962, she excavated the 7th-century Yassi Ada shipwreck (in Bodrum, Turkey) with the National Geographic Society and University of Pennsylvania.

[6] She was an active member of an international learned society that specializes in Roman pottery, which she became interested in as a result of her archaeological research underwater.

[7] In 1974, McCann joined the curatorial staff of the Metropolitan Museum of Art and led a lecture program related to archaeology.

She published her research on Roman sculpture while at the museum in Roman Sarcophagi in the Metropolitan Museum of Art, which won the Outstanding Book Award from the Association of American University Presses and was recognized as an Outstanding Art Book by the Thomas J. Watson Library in 1978.

[3] McCann presented her research through many venues—including a children's book that she contributed to and a general guide to some of her research—as a result of her "interest in the broad dissemination of archaeological information".