The Bosporus was closed to maritime traffic on Monday morning due to adverse weather conditions. Authorities announced that visibility dropped below a kilometer (half a mile) on a section of the Bosporus which necessitated closing the waterway to vessels seeking to enter or leave.

The waterway is among the busiest in Europe with cargo vessels and enormous tankers crossing into the Black Sea and/or heading to the Aegean via the landlocked Marmara Sea. It is also a highly dangerous passage for vessels due to its treacherous curves along the way and a narrow stretch. Maritime traffic is high throughout the day in the Bosporus, which also serves as a route for ferries carrying passengers crisscrossing between the Asian and European sides of Istanbul.

Ship traffic through the Bosporus rose in 2021, according to official data released last month as Turkey moved forward with a plan for an alternative waterway to ease the burden. The number of ships, including tankers, passing through the strait, which links the Black Sea to the Marmara and the Mediterranean beyond, increased by 147 to 38,551, Infrastructure and Transport Ministry data showed. Transits by ships longer than 200 meters (650 feet) and chemical tankers both hit their highest on record, at 5,306 and 2,701, respectively.

Kanal Istanbul, planned to be built further west of the Bosporus, is set to relieve congestion and improve safety on the waterway by diverting large ships with dangerous cargo away from population centers. Designed as an alternative global shipping lane, the canal will connect the Black Sea north of Istanbul to the Marmara Sea to the south and is estimated to cost around TL 75 billion ($9.2 billion).