Karoliina Stina Margaretha Rantamäki (born 23 February 1978 in Vantaa) is a Finnish ice hockey forward who currently serves as captain of HIFK Naiset of the Naisten Liiga (NSML), the premiere women's ice hockey league in Finland.
She has played with the Finnish national team at five Olympic Games and won bronze medals at the ice hockey tournaments in 1998 and 2010.
She has also represented Finland at thirteen IIHF World Women's Championships and has earned eight World Championship bronze medals (1997, 1999, 2000, 2004, 2008, 2009, 2011 and 2015).
Rantamäki has played with champion teams in both the Finnish Naisten Liiga and in the Russian Women's Hockey League.