Istanbul is surrounded on three sides by water. There is the Black Sea to the north, the Bosporus dividing the city, and the Marmara Sea along two edges of it. The Golden Horn is also an inlet that leads past the old city and up into what were once the suburbs. People have been using the sea to get around for millenia.
These days there are a lot of options. If you are in a hurry and know the schedule, you can take the deniz otobus, which is an enclosed catamaran. It is sort of like being in a plane. It goes quickly and so costs a bit more. There are some that cross the Marmara, which takes an hour or more, depending on where you are going. There are others that ply the length of the Bosporus. They generally travel in the mornings and evenings to suit the needs of commuters.
The regular ferryboats have been crisscrossing the Bosporus for almost two centuries. The design of the ferryboats has not changed much in that time. The main body of the ferry is enclosed, full of benches and in some there is an area with tables for drinking tea. There is an outside area at the bow and aft and along the sides there are benches outside. Tea sellers come along selling tea and juice and often there are also simit sellers. People often buy a simit and then throw pieces into the air for the seagulls to catch. On the longer routes, for example to the Princes Islands, there are also other sellers, usually useless plastic goods, like the lemon juicer that you just stick into the lemon, or cheap watches. At least they are entertaining. Smoking is prohibited inside and outside, but of course many people sit outside to smoke in the fresh air. These ferries are very dear to the people, and when the city was talking about retiring them all and using just the catamarans, there was a big protest and the idea was scrapped. These ferries are very relaxing, as you can breathe the sea air, feel the breeze, and enjoy the views of Topkapi Palace, the Galata Tower, and the Maiden’s Tower, among others.
Similar to the ferryboats, which are run by the city, there are vapurs, which are privately run. They are also big and have a more modern design. They are generally open on the top deck and closed in on the bottom deck. They usually leave when they are full, while the city ferryboats leave on a schedule. Some of the vapurs are small and accommodate only about 30 people. They also ply back and forth across the Bosporus. In recent years, the city has contracted with the large vapur and passengers can use their electronic tickets, like for other city transportation. The ones that are contracted usually follow a schedule, while the still independent ones wait for passengers.
In fact, the city has rebuilt many little limans, the small ferry stations. They are being used much more now because the land traffic is getting more and more impossible.
There is a also sea taxi. Apparently you can call it or meet it at certain places, and for a fair bit more than a land taxi, you can get to where you want to go in a much shorter time. The people who use it the most are probably those rich residents on the Bosporus.
You can also rent a copy of a caique, which is a long boat originally propelled by oars. There is a canopy at the back where in the old days the ladies or gentlemen would sit. Now it is motorized and can be rented for cruising the Bosporus or the Golden Horn.
Of course many people own their own boats. At some of the big bars and discos on the Bosporus, there are landings so those people can arrive by yacht.
At any of the many harbours, you can find boats to rent. These range from nice yachts to basic little boats, to great big boats that accommodate a few hundred people. These latter ones are often used for weddings or organized outings.
One day, I was in Karakoy, which is on the point of the Golden Horn and the Bosporus. I passed by some small boats and one of the boatmen called out “Taxi! Taxi!” I had time and was up for a little adventure, so I decided to do it. Usually I just walk across the bridge, but that day I forked out 2 lira, which is about $1 for the privilege of being taken across the Golden Horn to Eminonu, a trip of about five minutes. A grizzled old man was my captain. I was handed in to his blue motorboat and off we went. First we went way off and I told him and gestured that I did not want to go to Eyup, which is way up the Horn, but to Eminonu. Perhaps he was hard of hearing, as he didn’t speak very well, or perhaps he thought that because I was a foreigner I was not really speaking Turkish. Finally he swung around and headed in the right direction, pausing to haul a block of wood out of the water. In fact, being just centimeters above the water, I could see how dirty it was, full of plastic water bottles, empty plastic bags, soaked loaves of bread, and various other detritus. When we got to the other side, he pulled in and asked a passing man to help me out of the boat. I ended up walking almost as far as if I had walked across the bridge, but it was different from my normal route, and I had had a little adventure.
Often I took a little tekne (or putt-putt boat as I called them) like this to cross the Golden Horn from Karakoy, and a couple of times friends and I took one to to to Eyup, up the Golden Horn. Crossing the Golden Horn is fairly standard but we had to negotiate to go up the Horn, to about half of what the kaptan asked. One evening a group of us took one across the Bosporus to Uskudar. One of my friends is afraid of water, so his eyes were as big as saucers, but the rest of us enjoyed the cool of the water and the beautiful lights of the old city.
Of course there are other ships on the Bosporus, to the tune of about 100,000 a year (I read somewhere). These include fishing boats, cargo ships, tugs, pilot boats, and cruise ships, some of which are huge.
For the normal traveller, any one of the other options provide a very relaxing way to get somewhere in Istanbul, whether it is to cross the Golden Horn or the Bosporus or even the Marmara Sea. It is a wonderful experience to see the old and new city as you breathe the sea air, much as people have been doing for almost 8000 years.