As a physician scientist, Dr. Joseph MacInnis spent the first part of his career studying the performance of divers working at extreme depths under the sea. Between 1964 and 1994, he led thirty major expeditions and logged more than 5,000 hours below the Atlantic, Pacific and Arctic Oceans. In medicine, his work in decompression made possible dives that set records for depth and duration. In the 1970s, he designed and built the first Arctic dive station that allowed humans to explore below the polar ice cap. He led the first team of scientists to dive under the ice at the North Pole and was among the first to dive to the Titanic.

Since 1968, Dr. Joseph MacInnis has been president of his own science and education company. Undersea Research has had contracts with more than sixty major corporations and government agencies including The Department of Commerce and U.S. Navy in Washington and the Ministry of Science and Department of the Environment in Ottawa. To date, the company has produced five books and assisted in the production of 40 television documentaries and an IMAX film on the Titanic. The company's current focus is on environmental issues and counter terrorism. A mainstay of the company's current business is motivational lectures. During the past five years, Dr. Joseph MacInnis has spoken to more than 100 companies including Kodak, IBM, McDonalds, Merrill Lynch, AT&T, General Motors, Marriott Hotels, Hewlett Packard and Coca-Cola.

Since 1996, Dr. Joseph MacInnis has chaired the TD Financial Group's Friends of the Environment Foundation. The Foundation is a unique fund raising partnership between the TD bank and its customers. From the time of its inception, it has contributed 27 million dollars to some 11,500 environmental projects across Canada.