The intent behind her design was to enable her to attack enemy shipping in both open seas and close to shore with the least possible chance of being spotted before launching torpedoes at her targets.

As the two countries appeared on the brink of war in the autumn of 1905, the Royal Norwegian Navy carried out exercises involving almost its entire force.

[11] In the run-up to the war Sæl had been part of a large Norwegian naval manoeuvre during the International Yacht Racing Union's fourth annual Europe week sailing regatta, held in Horten 14 to 21 July 1914.

On one occasion in the autumn of 1924 the customs patrol boat Bjørnen discovered the smuggler ship Paul Weber off Halten in Sør-Trøndelag.

Sæl caught up with Paul Weber off the island of Frøya and opened fire, using live rounds, and lighted up the smuggler vessel with her searchlights.

[17] In the morning of 8 April 1940, on the eve of the German invasion of Norway, Sæl was docked at the Marineholmen naval base in Bergen between patrol missions.

[18] By 02:30 on 9 April she had finished coaling,[19] having been ordered to make war preparations the previous day,[20] and moved south towards her blocking position in the Lerøy area in the approaches to Bergen.

[21] When the German ships were spotted by Sæl they were at such close range that the Norwegians had to make evasive manoeuvres to avoid a collision[19] and were unable to launch a torpedo.

[22] As the Kriegsmarine ships passed her at only 10–15 metres distance, Sæl turned around and gave chase in the hope of catching up with the Germans and get within range for a torpedo shot.

As dawn was soon approaching Sæl's commander, Fenrik (Ensign) L. Gulbrandsen, decided to disengage and temporarily place his ship in cover behind the Bratholmen islet.

With the 7.92 mm Colt machine gun providing cover fire, Fenrik Gulbrandsen beached his vessel at full speed to save the crew.