The device, which installed by the Swedish Peace and Arbitration Society emits the message in Morse code.
It is hoped it will deter subs from Russia, which does not share Sweden’s acceptance of homosexuality.
The so-called Singing Sailor also features a flashing pink neon outline of a seaman cladonly in white underpants and a boater’s hat.
The figure can be seen gyrating its hips above the text ‘Welcome to Sweden – Gay Since 1944, the year when the country decriminalised homosexuality.
SPAS said on its website that its device was made to provide ‘interesting info for any submarines passing close by.’
In October last year, Sweden’s navy launched a massive hunt for a foreign submarine, suspected to be Russian, in the Stockholm archipelago.
The military later confirmed that ‘a mini submarine’ had violated its territorial waters, but was never able to establish the vessel’s nationality.
Following the incident, as well as several airspace violations by Russian jets over the last year, the Swedish government announced in April that it would raise defense spending by 10.2 billion kronor (£787million) for the period 2016 to 2020, largely due to concerns over Russia’s military resurgence.
SPAS said its campaign aimed at urging the Swedish government ‘to think in new ways instead of falling back on territorial defense, conscription and rearmament – the world doesn’t need more weapons.’
SPAS is the world’s oldest and Scandinavia’s largest peace organisation. It was formed in 1883 by the Nobel Peace Prize laureate Klas Pontus Arnoldson. The organisation is politically and religiously independent. SPAS is a non-profit organisation with about 7500 members.