ZSC Lions
Outside of Finland, Mertanen played in the Leistungsklasse A (LKA/LNA) with the ZSC Lions Frauen, the women's team of the ZSC Lions, during the 2011 playoffs and for the entirety of the 2011–12 season. With ZSC she won a silver medal at the 2012 IIHF European Women's Champions Cup.