Russian tankers turned off their tracking signals at more than double the normal rate in March, as 'dark activity' skyrockets following the invasion of Ukraine

• Russian oil tankers have averaged 12 "dark activities" per week since the invasion of Ukraine.
• That's more than double the normal weekly rate, according to data provided by Windward AI.

Russian oil tankers have averaged 12 "dark activities" per week since the invasion of Ukraine, according to Windward AI data shared with Insider. That's more than double the normal weekly rate, the maritime risk consultancy said.

"Going dark" — when vessels turn off their tracking systems — has been flagged by the US Treasury as one of several "deceptive practices used to evade sanctions" in the maritime industry.

By turning off its location data, a ship can obscure its final destination or hide other details about a vessel's movements. Before Russia was sanctioned, the country's oil tankers only went dark an average of five times per week, according to the Windward data.

Crude oil tankers "were barely involved in dark activities" prior to the sanctions and only went dark an average of 1.1 times per week, the Windward report says. But between March 19 and 25, the tactic skyrocketed. Data shows that Russian vessels carrying crude oil went dark 20 times that week.

Windward also reported that 33 vessels entered Russian water for the first time in the ships' history in March. Ship-to-ship meetings took place that could be long enough to transfer cargo to vessels without sanctions, though the frequency of those meetings matched typical levels, Bloomberg first reported.

At least nine superyachts owned by Russian oligarchs and tycoons — several of whom were sanctioned — similarly turned off their tracking signals this March.

All vessels of 300 gross metric tons or more that sail on international voyages must install tracking technology, commonly referred to as an automatic identification system, according to the International Maritime Organization's website.

Certain classes of vessels traveling on international voyages are required by international convention to broadcast their AIS location signal at all times.

In a sanctions advisory last May, the US Treasury warned that "vessels engaged in illicit activities may also intentionally disable their AIS transponders or manipulate the data transmitted in order to mask their movement."

Several countries, including the US and the UK, have barred both Russian oil and Russian vessels from ports following the country's invasion of Ukraine. The sanctions against Russian oligarchs have led to a flurry of highly scrutinized ship movement as superyachts and their owners attempt to escape seizure.

Turning off location data — on commercial or passenger ships — could make it harder for companies to avoid doing business with sanctioned entities or individuals.