The voyages will take place on 2 August and 9 August after the original four July sailings sold out earlier this week.
The eight-day itinerary departs from either Edinburgh or Greenock and has a port stop and excursion included every day.
Calls include Aberdeen, Inverness, Orkney, Oban, the Outer Hebrides and Belfast. Tours include trips to Loch Ness, Balmoral Castle, the Titanic Visitor Centre, the Callanish Standing Stones, and the Neolithic Ring of Brodgar henge and stone circle.
