[1]: 24–27  She originally intended to major in Ancient Greek, but after taking a biology course taught by George Howard Parker decided to change her course of study.

[1]: 35 [2][3] While a graduate student, she worked at Harvard University with Henry Bigelow, a founder and the first Director of the Woods Hole Oceanographic Institution (WHOI).

[8] In August 1941, she went to the Chincha Islands in Peru as a Faculty Fellow for Wellesley College's Committee on Inter-American Cultural and Artistic Relations.

[3] Sears was asked to come to Peru to study the plankton to determine if their reduced numbers led to birds dying,[9] which caused a disruption to the guano industry on the islands.

[1]: 9–13 [11][12] Sears was at sea during the attack on Pearl Harbor, and remained on the ship for three more months until she returned to Woods in Hole in March 1942.

[1]: 53–55 [2][13] Following a letter of support from Rear Admiral George S. Bryan, the head of the Hydrographic Office, Sears received a medical waiver for her arthritis and was accepted into the WAVES in January 1943.

[1]: 75, 85  Sears was assigned to the Hydrographic Office in Suitland, Maryland,[1]: 87  and began working to produce oceanographic charts ahead of planned amphibious assaults in Pacific Theater.

[1]: 92–93 [15] Within one month of her arrival, she published research on sea drift, to better help the Navy find crew and debris in the ocean after their ships sank or airplanes crashed.

[1]: 125–126 The Battle of Tarawa in November 1943 began with an amphibious assault that left US Marines exposed to enemy fire on a coral reef due to misjudging of the tides.

[1]: 184–186  In 1944, Sears raised concerns over the potential hazards of an amphibious landing in Palau; low tides over the surrounding coral reef were predicted for around the invasion, which would hinder the assault.

[1]: 189–190  Due to operational necessity, the Marines still conducted a landing on Peleliu, an island in Palau, despite the concerns raised by the Hydrographic Department.

Sears was able to narrow the list of potential beachheads, and highlighted the dangers of Okinawa being surrounded by a coral reef and experiencing high waves.

[18][1]: 253–254 When Sears returned to Woods Hole Oceanographic Institution, she was named a Senior Scientist in the Biology Department, a position she held until her retirement in 1970.

[19] Sears remained active at Woods Hole Oceanographic Institution until late in life, working with Joan Hulburt from an office in Bigelow Laboratory.

[21] Since women were not permitted to go to sea until many years later, Sears made her mark in marine science by editing the journals and books in which oceanographers published their results.

[28] On the occasion of her 80th birthday in 1985, Deep-Sea Research dedicated an issue to Sears,[29] noting that she "has probably played a greater role in the advancement of oceanographic studies than any other woman."

Radcliffe College honored Sears in 1992 with its Alumnae Recognition Award, given to "women whose lives and spirits exemplify the value of a liberal arts education."

[citation needed] She served on and was chairman of the committee operating the Children's School of Science in Woods Hole, and for 35 years was a Falmouth Town Meeting Member.