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41°07.170'N, 029°04.520'E Chart icon.png
Chart of Bosphorus

The Bosporus or Bosphorus, known by the Turks as the Istanbul Strait, (Turkish: İstanbul Boğazı) (Greek: Βόσπορος) is a strait that forms the boundary between the European part (Rumelia) of Turkey and its Asian part (Anatolia). The world's narrowest strait used for international navigation, it connects the Black Sea with the Sea of Marmara (which is connected by the Dardanelles to the Aegean Sea, and thereby to the Mediterranean Sea). It is approximately 30 km long, with a maximum width of 3,700 metres at the northern entrance, and minimum widths of 700 metres between Kandilli and Aşiyan and 750 metres between Anadoluhisarı and Rumelihisarı. The depth varies from 36 to 124 metres in midstream. Most of the shores of the strait are heavily populated, since the city of Istanbul (with a metropolitan population in excess of 11 million) straddles it.

The Bosphorus has a strong, south going current which can run at 3.0 - 4.0 knots in places, especially where the Strait narrows. Navigating its length from the Sea of Marmara up to the Black Sea is like proceeding against a river. However, the current is less strong near the banks and there is even a counter-current in places. To compound the problem for a N-going yacht, the prevailing wind usually blows down the Strait and is funnelled where it narrows. Strong winds of 20-25 knots can make progress all but impossible. In addition, there is very heavy traffic in the Strait, with huge tankers and bulk carriers bringing oil and other materials between the ports of the Black Sea and the Mediterranean, plus hordes of local ferries and tour boats criss-crossing the waterway and tearing up and down its banks. The heavy commercial traffic is controlled within the marked shipping lanes but outside these, near the banks, there is a virtual free for all.

The Blue Mosque, the most famous Bosphorus landmark

Commercial traffic is controlled by a series of radio operators on different channels for the various sectors of the Strait. From S to N the sectors and frequencies are Kadikoy (VHF channel 14); Kandili (VHF channel 13); Kavak (VHF channel 12) and finally Turkeli (VHF channel 11). It is important for a yacht transiting the Strait to listen out on these channels as it proceeds up the waterway, since instructions are given to all vessels as required on these frequencies. A one-way traffic system operates for safety reasons. Usually N-going ships transit the Strait from midnight to noon local time and S-going ships from noon to midnight. It is thus necessary to ‘look both ways’ if you are transiting over the midday period. See below for detailed instructions on transiting.

In addition to the famous landmarks of the Blue Mosque, the magnificent Agia Sofia, the 19th century Dolmabahce Palace of the Ottoman sultans, and the 15th castle of Rumeli Hisar (built by Mehmet the Conqueror prior to the conquest of Constantinople), there are numerous impressive Ottoman period mansions to admire on both sides of the Strait. As a transiting yachtsman, you get a privileged view of all these attactions for the price of nothing more than (quite a few) litres of diesel.


1158 Istanbul Bogazi N Part NW Turkey
1159 Istanbul Bogazi S Part NW Turkey
1198 Istanbul Bogazi NW Turkey
55047 Southern Entrance to the Istanbul Bogazi (Bosporus)
55048 Istanbul Bogazi (Bosporus)
2921 Bosphorus


For most of the time, even in settled weather, winds blow down the Strait from the N and can funnel strongly in the narrower parts. It is not advisable to attempt a transit in strong winds from N unless your engine is exceptionally powerful.

Also see Turkey.


  • Bosphorus Control - VHF channels 11,12, & 13

Also see World Cruiser's Nets.


The Strait should only be transited by daylight - a night transit would be folly. The convention is that pleasure craft should stay close to the European side of the channel, out of the shipping lanes, and this is particularly true if northbound. By staying as close to the shore as possible, the worst of the adverse current can be avoided and in certain sections there is even a weak counter-current. Where the Strait narrows between Kandilli and Aşiyan and between Anadoluhisarı and Rumelihisarı, the current is especially strong and there is nothing for it but to plough on. A southbound yacht may also choose to stay on the European side, although many opt to sail down the Asian side (especially if there is a decent wind to assist progress) if continuing to the Princes Islands or the Setur marinas at Kalamis/Fenerbahce.

A yacht capable of a constant speed of 6.0 knots through the water should be able to transit the Strait from the entrance at Kadikoy up to Turkeli on the European side or Poyraz on the Asian side within three hours, assuming it stays out of the strongest currents. The return journey, as one would expect, takes barely two hours at the same speed.

Warning: If crossing the Strait, it is essential to cross perpendicular to the shipping lanes and to keep careful watch for commercial traffic. The safest places to cross are generally at the north end near Poyraz or the south end from Kadikoy across to the E cardinal mark at the Ahirkapi Bank. Do not attempt to cross anywhere near the Golden Horn, as this is the busiest part of the entire Strait.

Warning: Note that the pillar marks and buoys marking the main shipping channel are arranged from the Black Sea to the Sea of Marmara. In other words, a N‑bound yacht will find all the starboard marks on the European side of the channel and the port marks on the Asian side. Although a yacht should not be anywhere near most of the shipping marks, it is important to know which side of them is in the shipping lane and which side isn’t!

Danger: Very often there is a heavy fog and the Strait is closed to traffic.

Topkapi Palace from Bosphorus
Dolmabahce Palace from Bosphorus
Rumeli Hisar castle
Typical Bosphorus mansion


See Turkey.


There are several small harbours along the European bank (really just inlets out of the current) such as Bebek, Istinye, Buyukdere and Tarabya. However, they are usually crowded with local boats on moorings along the quays or on buoys. There is generally no room for a visiting yacht and it would be unwise to plan on stopping off at any of them. In an emergency, however, it may be possible to pick up a buoy, but you should be prepared to move off if the owner returns (or have a very good excuse ready). Anchoring is inadvisable anywhere along the Strait as most of the anchorages are relatively deep and exposed to the currents and eddies as well as heavy wash.

Most yachts heading N or S through the Strait tend to stop either at Turkeli on the European side or Poyraz on the Asian side before heading down to one of the Istanbul marinas or the Princes Islands or up into the Black Sea.

Key to symbols: |Port of entry icon – port of entry |Harbour icon – harbour |Anchorage icon – anchorage |Needs data icon – needs data ||
  • Istanbul Istanbul /wiki/Istanbul Port of entry icon – port of entry |Marina icon – marina |
  • Turkeli Turkeli /wiki/Turkeli Harbour icon – harbour |Needs data icon – needs data |
  • Rumeli Rumeli /wiki/Rumeli Needs data icon – needs data |
  • Tarabya Tarabya /wiki/Tarabya Anchorage icon – anchorage |
  • Poyrazkoy or PoyrazPoyrazkoy or Poyraz/wiki/Poyrazkoy Harbour icon – harbour |Anchorage icon – anchorage |


Submit details/contacts of cruiser's "friends" that can be contacted in advance or on arrival - who can offer information and assistance to our cruising "family".

Also see Bosphorus Guide to mariners.


List links to discussion threads on partnering forums. (see link for requirements)



See Turkey.


We welcome users' contributions to the Wiki. Please click on Comments to view other users' comments, add your own personal experiences or recommend any changes to this page following your visit.

  • Transiting Bosphorus is nerve racking but also a magnificent and unforgettable experience. --Istioploos
  • In spite of the adverse currents and winds and the hurly-burly of ferries and commercial traffic, a transit of the Bosphorus is one of the most interesting three hours you can spend in a cruising yacht. --Athene of Lymington 15:13, 13 June 2011 (BST)

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This is a usable page of the cruising guide. However, please contribute if you can to help it grow further. Click on Comments to add your personal notes on this page or to discuss its contents. Alternatively, if you feel confident to edit the page, click on the edit tab at the top and enter your changes directly.

SailorSmiley.gifContributors to this page

Names: Istioploos, Athene of Lymington, Rr7

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