The island houses a 130 53 TK Coastal artillery battery, a maritime surveillance station and a corrosion laboratory of the Aalto University.

Since then the island fortress played a significant role in the evolution of coastal artillery in Finland and in the defense of capital of the nation.

[1] During the independence of Finland, the Isosaari fortress was a unit under the Suomenlinna Coastal Regiment, responsible for the training of conscripts and all other functions on the island.

In addition to these, firing position NCOs were trained, as well as logistics men, scribes, headquarter couriers and gunsmiths.

The standby functions included guard duty, maritime surveillance, and the ability to fire warning shots from one of the 130 mm cannons on the island.

In addition to this, the men of the fortress were responsible for guard duty at the Naval Academy on the island of Pikku-Musta in Suomenlinna.

During 1984–2008 the Defence Forces operated a weather station on the island, making observations on behalf of the Finnish Meteorological Institute.

Every three hours they sent a SYNOP telegram, which included information on the temperature, the relative humidity, wind speed and direction, quality of clouds and their lower limit and total number, as well as the barometer reading, visibility and meteorological phenomena.

The Amphion was trying to sound the Viipuri Channel, but encountered fire from both Santahamina and Samu Matosaari in Laajasalo, as well as from five gun boats.

I. H. S." Towards the end of the century, a British wife of a Finnish merchant erected a permanent stone on the grave, on to which the text was copied.

Representatives of the Royal Navy and the British ambassador to Finland with his spouse have placed a wreath on the grave on the occasions of the 100th and 150th anniversaries of the battle.

[6] In 1918, the Isosaari Prison Camp was operated on the island, to which members of the Red Guards and Russian soldiers were placed.

[citation needed] The island has two restaurants, two beaches for swimming, a shooting range, a barracks building, three saunas next to the shore and a number of quarters for the staff.