In 1909, Ängsö was declared a national park, one of the first in Sweden - and the smallest. Thanks to the professor Lars-Gunnar Romell, who in the 1940's led the extensive clearing work on Ängsö, it has managed to preserve the beautiful farmland from the 1700's. In early summer, you'll be met by all the flowers that the Swedish archipelago has to offer. Over 400 different plant species have been inventoried here including large stands of various orchids such as Adam and Eve, frog, lesser butterfly, common twayblade and bird's nest.

There is a very rich bird life here. The purpose of the national park is to "preserve an older farmland” and has succeeded by taking care of landscapes carefully and according to old methods, including grazing animals. Ängsö has easily-accessible trails, many of which are wheelchair friendly. Electrical wheelchairs may be borrowed on the island.