Island Ist in the Zadar archipelago, is connected to Zadar with a fast ferry / catamaran as well as a car ferry in the main season. The car ferry from Zadar to Ist, only operates a few days a week in June, July, August and September, but considering the size of Island Ist, you also do not really need a car on the Island.
The car ferry to Ist, sail from Zadar via Island Rivanj, Island Sestrunj, Island Zverinac and Molat on Island Molat before arriving at Ist the sailing time is about 4 hours. Once a week the catamaran sails directly from Zadar to Ist, the other days of the week the catamaran sail via, Brgulje, Zapuntel and Molat on Island Molat.
The adult ticket price from Zadar to Island Ist is 40 kuna with the catamaran and 30 kuna with the car ferry, there is no return discount on the tickets, so when you travel back from Ist to Zadar you will have to pay the same price. If you bring a regular car to the island the price is 170 kuna one way plus the tickets for the passengers.