Hernesaari is a subarea of the Länsisatama district in the southernmost part of Helsinki. It consists of the peninsula west of Eira and the former islands of Munkkisaari and Hernesaari, which have been connected to it by land reclamation. Administratively, Hernesaari belongs to the Ullanlinna basic district, which in turn is part of the broader Southern major district of Helsinki.