The national bomb shelter called in took the suspected object with it and on Wednesday the authority confirmed that it was in fact a scarlet grenade which will now be destroyed.
"It is not uncommon for such items to be found at regular intervals," said police spokesman Stefan Dangardt in the Bergslagen region.
In connection with the finding of the grenade, the immediate area was blocked off in the marina. However, it was never relevant to evacuate the properties nearby.