But it’s not really true. Switzerland has no naval branch of its armed forces.
It has a dozen or so of 10t patrol boats armed with a single 50cal MG for its lakes, and those are organized in a single motor boat company, which is staffed and manned by the military engineers branch.
Their duties are supporting the border guard (police) on the lakes against trespass/ smugglers and assisting (civilian) search& rescue.