HSwMS Hvalen was a submarine of the Swedish Navy.

Constructed in Italy, the submarine sailed the entire way to Sweden for her commissioning unaccompanied.

[1] In October 1915 she became involved in a diplomatic incident between neutral Sweden, and Germany, which was then engaged in fighting Britain in the First World War.

Following a series of sinkings of German cargo ships and naval vessels in the Baltic Sea by British submarines entering the Baltic through the (Swedish-controlled) Öresund straits, a German warship opened fire on Hvalen killing a crew-member.

[3] Compensation was later paid to the widow of the crew-member and an apology was issued.