When on Insel Mainau, don't miss the impressive Butterfly World: It is a gigantic hall, with a Tropical living environment: large trees, unique flowers, waterfalls and rocks, and in-between all of those, thousands of variously sized and colored butterflies fly freely. It is a really beautiful sight. Keep in mind that the indoor temperatures are very high (Tropical climate), and it is recommended to take off layers of clothing before entering - it is quite a heat shock.