Update, March 24, 10:30 a.m.: Costa has decided to cancel its planned port calls at Odessa and Yalta, scheduled for Costa Deliziosa's Black Sea itineraries in April, May and June. They will be replaced with more time in Istanbul and a stop at Burgas, Bulgaria.

(4:25 p.m. EDT) -- After holding off for several weeks to see how events developed in the Crimea peninsula between Russia and Ukraine, several cruise lines have changed their Black Sea itineraries to avoid the ports of Odessa, Sevastopol and Yalta.

Azamara, Oceania, Regent Seven Seas, Windstar and MSC have all substituted ports in other countries, including Turkey, Romania, Georgia and Bulgaria. Some sailings will also spend more time in Greece.

For its June 12 sailing, Azamara Quest has replaced the three cities with Bartin in Turkey, and Volos and Nafplion in Greece, as well as adding an extra day in Istanbul.

MSC Cruises has also added Volos – site of the Meteora monastaries, perched on rocks - and Varna, a seaside resort in Bulgaria to the April and May sailings of MSC Sinfonia.

Regent Seven Seas and Oceania have substituted Batumi in Georgia, and Trabzon in Turkey, while adding an overnight in Constanta, Romania. The latter line has kept two scheduled Black Sea cruises on Riviera intact, however.

“For the many guests interested in traveling to destinations visited on our original Black Sea itinerary, we have a sailing in May and September to accommodate those guests,” Oceania said in a statement.

Windstar has decided that Star Pride will not call on Yalta or Sevastopol, substituting Amasra and Samsun in Turkey instead. The line will still call on Odessa, as the city is not located in Crimea.

Other lines are still in wait-and-see mode. Silversea has made no changes to Silver Wind's sailing to the region, slated for late April. Holland America is waiting, although its ship, Prinsendam, isn't sailing to Crimea until October. Cunard, Costa and Viking, which has river cruises scheduled for the Dnieper River in Ukraine, have not changed itineraries either.

Cruise Critic has yet to hear from a few lines with scheduled Crimea stops, including Seabourn and Princess.

As Cruise Critic reported earlier in the month, cruisers with planned trips to the Black Sea during the spring and summer were debating whether to follow through with final payment. Others who were still going worried about whether they now needed a Russian visa to take private tours in Sevastopol and Yalta.

---Chris Gray Faust, Destinations Editor