Lachen is a municipality in March District in the canton of Schwyz in Switzerland. Lachen is first mentioned around 1217–22 as de Lachun…Lachen is a municipality in March District in the canton of Schwyz in Switzerland. Lachen is first mentioned around 1217–22 as de Lachun. Lachen has an area of 2.4 km², as of 2006. Of this area, 26.7% is used for agricultural purposes, while 5.8% is forested. Of the remaining land, 62.1% is settled and the remainder is non-productive.