Istanbul skyline

(July 8, 3:46 a.m. EDT) -- Most cruise lines with calls in Istanbul have cancelled all port stops following the June 28th airport bombing which killed 42 people, with one line still monitoring the situation.

Celebrity Cruises, Cunard, Princess Cruises, Seabourn, Silversea, Uniworld, Windstar and Holland America Line were all due to call in at Istanbul in the coming days and weeks; all but HAL and Uniworld have now canceled.

Neither the U.K.'s Foreign & Commonwealth Office nor the U.S.'s State Department have altered their travel advice to Turkey, which is usually the trigger for travel companies to cancel or alter travel plans. The U.S. currently has a warning for the southeast part of Turkey bordering Syria and Iraq.

The bombing is the sixth -- and deadliest -- terrorist attack in Turkey this year. The second Istanbul bombing in March led to a number of lines altering their itineraries, including Viking.

Crystal, Disney and MSC Cruises had already announced that they will not stop in Turkey in 2016; Celebrity Cruises had already canceled overnights in Istanbul. What complicates the issue is that many cruise lines on Eastern Mediterranean itineraries embark or disembark in Istanbul, meaning that passenger flights may have to be changed on short notice.

Here's where the lines stand:

Celebrity Cruises. Celebrity Cruises has canceled all calls in Istanbul. A spokesperson said: "Celebrity Cruises is aware of the situation in Istanbul, Turkey, and our thoughts and prayers are with all those affected by the attack. After discussion with our Global Security team in Miami, we have decided to cancel all of Celebrity Cruises' upcoming calls to Istanbul, Turkey, and replace them with Athens (Piraeus), Greece.This decision was made in the interests of our guests' safety and we apologize for the impact on their cruise. Our guests' holiday time is precious and we did not take this decision lightly. The safety of our guests and crew is always our foremost concern. We are currently finalizing the details of these itinerary changes and will communicate with our guests or their travel agents as soon as we have additional details.

Cunard. Cunard has canceled all calls to Istanbul for the rest of this year. Queen Victoria was due in on July 18 to spend a night in Istanbul, but this will now be replaced by two Turkish ports -- Volos on the 18th July and Marmaris on July 20; and Volos on Aug 29 and Marmaris on Aug 31."

Celestyal Cruises. Celestyal has no more Istanbul stops, but will continue to call at Kusadasi and Cesme.

Holland America Line. The line has issued the following statement: "Holland America Line has been closely monitoring current events in Istanbul, Turkey, and, out of an abundance of caution, we have made the following changes to cruises visiting the port on the below sailing." Eurodam, which is scheduled to depart from Venice for an Eastern Mediterranean cruise July 17, has canceled stops in Istanbul and Mytilene, Nisos Lesbos, Greece. Instead, the ship will visit Mykonos (July 22), Kusadasi (July 23), Rhodes (July 24) and Crete (July 25).

The line also said, "Shore excursions booked in affected ports through Holland America Line will be refunded and taxes, fees and port expenses will be adjusted accordingly."

Princess Cruises. After previously canceling Royal Princess' July 7 call at Istanbul, the line has replaced its July 28 call with Rhodes. The ship is still slated to visit Kusadasi July 27 and August 1.

In a statement released earlier this month, Princess said, "...the remaining Istanbul schedule for 2016, will be evaluated over the next couple of weeks and decisions will be made based on the available information and circumstances at the time. The smaller Turkish ports such as Kusadasi will remain on the schedule for the present time. Guests who have prepaid Istanbul shore excursions will be reimbursed via their onboard account."

Seabourn. Seabourn has replaced its Friday call for Odyssey, originally slated for Friday. Noted the statement: "After a very careful and thorough review, Seabourn has decided to replace the July 2, 2016 turn port of Istanbul with Piraeus (Athens). Seabourn is closely monitoring the situation in Istanbul. The company analyzes information regarding safety and security from many sources, which includes liaising with government intelligence agencies and on-the-ground port security assessments. We are in the process of assessing other upcoming scheduled visits to Istanbul. We will provide an update in the next 24 hours."

Silversea. Silver Spirit was due to call at Istanbul next Wednesday (27th) and spend the night, but it has replaced Istanbul with Athens and removed Istanbul from all itineraries for the whole of next year. A spokesman said: "...following an increased number of travel advisories distributed by international agencies, we are taking the proactive step to remove Istanbul from itineraries in the immediate future and through the whole of 2017, and replace it with a stop in Athens, Greece."

Uniworld. Uniworld has several Eastern Europe river cruises flying out of Istanbul and are planning on operating all as scheduled. However, the line has stated that passengers booked on any itinerary featuring Istanbul that depart within the next 60 days (through August 27, 2016) may re-book without penalty on any future 2016 or 2017 itinerary and departure date.

Windstar. Windstar announced the revision of 16 cruises, replacing scheduled embarkation/disembarkation port calls in Istanbul, Turkey with the port of Piraeus (Athens). Additionally, scheduled mid-cruise ports of call in Kusadasi and Bodrum on affected sailings will be canceled and replaced with visits to the Greek island of Kalymnos and seaport of Nafplio. The changes affect 7-day cruises aboard the 148-passenger Wind Star originally scheduled to embark alternate Saturdays in Athens or Istanbul. The first canceled port call to Istanbul was scheduled for July 9. Passengers sailing on the July 2 cruise will now disembark in Athens on July 9, and those booked on the July 9 cruise departure will now board the ship in Athens, also disembarking there as originally scheduled on July 16. The revised all-Greece 7-day itinerary will sail roundtrip from Athens keeping originally scheduled visits to Mykonos, Santorini and Rhodes, and adding Kalymnos and Nafplio, split by a day at sea. Cruises depart from Athens on 16 consecutive Saturdays from July 2 to Oct 15, 2016.

Windstar is in the process of contacting all booked guests and their travel agents with details on cruise and travel itinerary changes and will assist with alterations to travel plans.

Cruise Critic members are speculating whether any of the lines will make itinerary changes, as well as offering sympathies for the city and country.

Nimiq said on the HAL Boards: "I think we are one of the next ship going there Eurodam in July. Not sure want to go anymore :-("

And chefestelle: "It's one of my favourite places I've been. I so want to go back again. My heart goes out to the Turkish people who will suffer so much from this horror."

--By Adam Coulter, U.K. Editor and Chris Gray Faust, Senior Editor