Next April, we are going to be on a 12-day tour through Slovenia and Croatia. It originates and ends in Venice. On our last day, in Venice, we have some time to explore. We have already been to Venice before and would like to take a day/afternoon trip to the caves in Postojna on our last day of the trip. Are there any bus tours from Venice to the caves, and is it possible to go from Venice to the caves, see the tour, which I believe is 1 1/2 hours long, and return to Venice later that same day?