Cora Mildred Maris Clark was born at Auckland, New Zealand, on 3 March 1885 to Cora Juliett Meurant and her husband, Richard Maris Clark, an insurance manager. From about 1890 the family lived in Dunedin. With her younger sister Elvira, Cora attended Otago Girls' High School where the two girls became enthusiastic hockey players. Together they joined teams in one of a handful of clubs around Dunedin playing regular Wednesday and Saturday matches.
With some prompting from her good friend Alice Woodhouse, Cora Maris Clark (as she was known throughout her life) was persuaded to take the chair when members of the various clubs formed the Otago Ladies' Hockey Association at a meeting held at the start of the 1906 season. Woodhouse was elected secretary and treasurer. Typical of the early years of hockey, Clark was organiser, umpire and representative player all in one; she was one of four players who regularly acted as referee in an early game before playing in her own match. In 1904 she took part in the major fixture of these years, playing for Otago in the annual game against Canterbury.
Clark's term of chairing the Otago association was curtailed when her family returned to Auckland in 1907. Her enthusiasm for hockey was undimmed by the move, and with Elvira she joined a team playing for the Moana Club of Devonport. The team was unbeaten throughout the season, defeating the previous year's champions on two occasions. However, Cora found the organisation of the game in Auckland in a parlous state. She applied herself energetically to encouraging new players into the sport and to setting the competition on a stronger footing. In 1908 she became secretary of the Auckland Ladies' Hockey Association, by which time the number of teams had dwindled to four. Clark wrote to headmistresses of the Auckland girls' secondary schools seeking new players and offering her services as coach. The Ladies' College, Remuera, was the only school to accept the offer of coaching.
In September 1908 Cora Maris Clark and Eileen Schischka travelled to Wellington as the two Auckland delegates to a meeting called to establish a national women's hockey organisation. She met tough opposition in the form of delegates coming from districts where women's hockey had developed under the aegis of male control. When it came to defining the constitution of the new organisation, Clark strongly advocated that office-holders should be women. Her motion to this effect was ridiculed and roundly defeated. Nearly 50 years later she vividly recalled the 'squashing' she was dealt by the men at that meeting. Arnold Izard, who chaired the meeting, was elected first president of the New Zealand Ladies' Hockey Association in April 1909.
Despite never holding office in the national organisation, Clark continued to be active in the sport. She played centre half in the Auckland representative team, and was coach, selector and manager in 1909 when the team competed at the first national tournament played under the auspices of the NZLHA. They finished runner-up to the defending champions, host team Hawke's Bay. Clark introduced the four-piece knitted cap, which became a standard part of playing garb for hockey players until 1950, and was successful in winning concessions to players' skirt lengths: eight inches from the ground for forwards, six inches for backs.
After two years with Clark as secretary, the Auckland competition had expanded to encompass a number of teams playing in two grades. Clark's own hockey career was interrupted in 1911 when she began nursing training at Auckland Hospital. A favourable duty roster the following year enabled her to take up play again, this time for a new club, Aotearoa. Like many sports clubs around this time it was an extended network of friends and neighbours. Cora and Elvira played in a team comprised of young women from only four families.
Clark remained an outstanding player. In 1914 she was nominated for the first national women's side to play New Zealand's inaugural international visitors, the touring All-England team; unfortunately, work prevented her from taking part. She continued to play, and to coach women's hockey, and was in demand as a respected referee, taking on control of men's games as well as women's. Before there was a separate women's hockey umpires' association or qualification, Clark was accredited an umpire by the men's association, the first woman to be so recognised.
Cora Maris Clark was first registered as a nurse in 1915. Apart from a few years at Auckland Hospital, most of her career was spent in private nursing in Auckland city and, for a time, in Tolaga Bay. She did not play a leading part in the revitalisation and expansion of women's hockey in the years following the First World War. That task was taken up by people such as Pearl Dawson, Ethel Moore and Enid Sonntag. However, Cora's devotion to a game played and organised by women remained steady throughout. In 1953, when reflecting on the history of women's hockey, she said her greatest satisfaction was the opening of Melville Park in 1939 as a sportsground for women. An enthusiastic player of what was a thoroughly physical contest (against mud and rough playing fields as well as the opposition), Clark held that no limitations should be placed on how women played or organised what she saw as 'their' game.
In 1954 Clark was made a life member of the New Zealand Women's Hockey Association. At the time of the association's golden jubilee in 1958 she was one of the few remaining members who could recall the early years of the game. Her 'Reminiscences' supplied for the jubilee history were as spicy and direct as her original submissions to the inaugural meeting of the association. Cora Maris Clark did not marry. She died in Auckland on 30 June 1967.