The Comrades Marathon is an ultramarathon of approximately 89 km (approx. 55 miles) which is run annually in the KwaZulu-Natal Province of South Africa between the cities of Durban and Pietermaritzburg. It is the world's largest and oldest ultramarathon race. The direction of the race alternates each year between the "up" run (87 km) starting from Durban and the "down" run (now 90.184 km) starting from Pietermaritzburg.

The event on Sunday 11th June 2023 is the 'down' run of approximately 90km from Pietermaritzburg to Durban.

The field is capped at 25,000 runners, and entrants hail from more than 60 countries. In all but three runnings since 1988, over 10,000 runners have reached the finish within the allowed 11 or 12 hours. With increased participation since the 1980s, the average finish times for both sexes, and the average age of finishers have increased substantially.

Runners over the age of 20 qualify when they are able to complete an officially recognised marathon (42.2 km) in under five hours (4h50 for 2019). During the event an athlete must also reach five cut-off points in specified times to complete the race. The spirit of the Comrades Marathon is said to be embodied by attributes of camaraderie, selflessness, dedication, perseverance, and ubuntu.