Opulent superyachts owned by Russia's oligarchs have been hitting rough legal waters as authorities around the world act on international sanctions to pressure those close to President Vladimir Putin. A number of vessels, worth an estimated total of at least $1.6 billion, have been seized so far, with the latest taking place in London on March 29. Here's a look at several high-profile seizures and the owners behind them, as well as some that are in the sights of authorities, including one that has been linked to Putin himself.