This link goes to a page that updates so you may have to scroll down to the headline Russia’s accusation after the bridge attack renews attention on sea drones.

Russia Fires Drones and Missiles at Southern Ukraine

Depending on how they are operated, the boats, also called marine drones or unmanned surface vessels, can be hard to detect. They can carry enough fuel to travel far and enough explosives to detonate with power.

And while they might cost in the low hundreds of thousands of dollars, they can do millions of dollars in damage, embarrassing the Kremlin and, as evidenced by the harsh comments of pro-Russian military bloggers after Monday’s attack, drawing further criticism of a military leadership roiled by last month’s mercenary uprising.

“The problem for the Russians is that there’s no sure way to defend itself against these boats,” said Sam Bendett, an expert in drones and Russia’s military at CNA, a research institute in Virginia. . . .If two waterborne drones did detonate explosives at the Kerch Strait Bridge, Mr. Bendett said, they would probably have been at least 15 feet long and packed with hundreds of pounds of explosives, along with the fuel, probably diesel or gasoline, for the voyage.

The vessels would probably have been launched from land, Mr. Bendett said, and guided by satellite, perhaps via the Starlink system that is widely used for internet access in Ukraine. He said they would have traveled across the Black Sea at a speed slow enough to minimize their wake and foil radar detection.

No video of the actual event, just views from vehicles on the bridge deck or perhaps highway cameras.