Aquatis is a major freshwater aquarium and vivarium in Lausanne, focused on rivers, lakes, reptiles, amphibians, and aquatic ecosystems from Switzerland and beyond. It is polished, family-friendly, and quite different from the city's art and Olympic museums.
The site is outside the old-town core but easy to plan as a dedicated half-day. It is especially useful in bad weather or with children, though adults interested in ecology will also find enough substance.