On 5 March 1940, the merchant vessel SS Grutto was on her way from London to Rotterdam, loaded with general cargo. Around the afternoon, the vessel sailed past Gravesend, where the pilot disembarked. After that, nothing was heard of the Grutto and her crew of eighteen. The next morning, several ships found wreckage of the Grutto. This included a part of the wheelhoude roof. The roof was torn off by a powerful explosion and blown away. On 29 March, the bodies of a sailor and the first officer washed ashore in Callantsoog and Texel. After the war, it became clear that the Grutto had been torpedoed by the German submarine U-17. U-17 had sailed from Wilhelmshaven on 29 February and was patrolling west of Walcheren. Walter Behrens, the commanding officer, estimated the tonnage of the Grutto at 4000 (in reality it was 90 tons). Three days before, U-17 had torpedoed MS Rijnstroom at roughly the same location.

Due to the torpedo attack, the wreck of the Grutto broke in two parts. These are at a maximum depth of 32 meters, in a straight line. They are about 55 meters apart. The front of the ship heels about 45 degrees to starboard. The rear is about upright, but severely tattered and collapsed.

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