Rowing and kayaking are similar, though far from identical sports, in which participants in boats use some type of implement (e.g., oar, paddle) to propel themselves or their teams along a body of water. This YouTube video discusses the differences between the two disciplines.
Each of these sports has a dominant figure who compiled a gold-medal-winning streak lasting a full generation.
Kayaker Birgit Fischer, first representing East Germany and then, from 1992 onward, a unified Germany, won gold medals in 6 straight Olympiad: 1980, [1984 boycotted], 1988, 1992, 1996, 2000, 2004. She wanted to come back and participate in the London Games, but her physician put an end to that, based on some undisclosed medical-examination results.
This year's host country is home to one of the all-time greats in rowing. According to the Wikipedia, Sir Steven Redgrave “won gold medals at five consecutive Olympic Games from 1984 to 2000.”