In Haltia there's also interesting temporary exhibitions indoors:
Vuosaari by Antti Koli 1.6.-20.9.2020
Exhibition Still Standing by Mia Honkanen 11.8.-6.9.2020
Best of "Nature picture of the year 2016-2018"
Come to Finland -posters from the 1900s
A textile work of Forest nature diversity, made by students at Omnia. Read more in Finnish
Archive of the previous Temporary exhibitions (with information in English):