Welcome to Adalar (the Islands), a district of Istanbul, Turkey which includes nine islands. I doubt you will have time to explore all nine islands in a single day. There is about a 25 minute commute between each island by boat of course. It took me maybe 3 hours to explore only part of one island. The nine islands are named Büyükada, Heybeliada, Burgazada, Kinaliada, Sedefedasi, Sivriada, Yassiada, Kasik Asasi, and Tavsan Adasi.
Getting back to the ferry from the viewpoint isn’t hard either. Once you come back down from the high level views and hikes, there will be taxis awaiting to take you back. If you do not want to ride in a taxi and prefer to ride back by bus then the buses run very often. The buses will pick you up at the exact place where you would have originally gotten off. There are also ticket machines at the Adalar ferry, and at the Adalar bus stop. I thought it was more convenient to just purchase a card at the ticket machine which already comes with money on it, and with the card, you are also able to add money on it. If you are traveling with other people, maybe family or friends, this would be a good option because you could swipe your card at the turnstiles for everyone. Prior to boarding the Princes’ Island ferry, I purchased a Istanbul card for 29 TL, and I just added 150-200 TL on the card. This took care of a roundtrip ferry ride, and a roundtrip bus ride on the island, all for two people.
It was recommended to explore Büyükada, which means “Big Island” in Turkish, mainly because it is the largest island, and the 6th-century Hagia Yorgi Church is its most popular attraction. It takes maybe 30 minutes to get to the top where the church lies, and once you arrive you will be met with its panoramic views. Nearby are the pine forests of Dil Burnu National Park. There is also a Museum of the Princes’ Islands that has exhibits on the islands’ history. I didn’t get to go. I mostly got to explore viewpoints on top of observatory-like decks. If you are considering a day trip to the Islands, I highly recommend it. You will also find many restaurants, cafes, museums, and hotels.