Marithy is a former international rugby player, having captained South Africa and representing South Africa in both the 15 man and 7 man codes. She is currently coach & project manager of a 7s Rugby Academy in Franschhoek having completed a World Rugby level 1 & 2, Sevens Coaching Certificate in 2017. In her role she identifies players to become part of the Academy, both boys & girls, run tests with them and finally select a final squad to coach. She also runs the 7s Rugby program as Head coach at Bridge House School in Franschhoek. She coaches the basics of rugby and work with children aged from 9 till 15.
During her career at the Sevens she has been participated at the Commonwealth Games in Brisbane, Australia, qualified for the World Cup in San Francisco in July 2018 and Cup Winners of 2016 Hong Kong Invitational tournament where she was vice-captain. Marithy is part of the Women Sport Leadership Academy as one of five female coaches.