At the 1983 Summer Universiade in Edmonton, Mosse won a bronze medal in the 200-metre butterfly.

[3] At the 1985 Summer Universiade in Kobe, Mosse won a silver medal in the 200-metre butterfly.

[1][5] Mosse developed his career in the United States but continued to swim for New Zealand, gaining a bronze medal at the 1988 Olympics in Seoul, Korea.

He is now a merchant banker in San Francisco, but continues to be involved in swimming and is a regular commentator for TVNZ (including Beijing, 2008).

In the 1989 Queen's Birthday Honours, Mosse was appointed a Member of the Order of the British Empire, for services to swimming.