 Some 60 fish species are found in this area and recreational fishing is popular.Major islands in Helsinki include Seurasaari, Vallisaari, Lauttasaari, and Korkeasaari – the lattermost being the site of Finland's largest zoo.Other noteworthy islands are the fortress island of Suomenlinna (Sveaborg), the military island of Santahamina, and Isosaari.