The eco-warriors were on Greenpeace ship Arctic Sunrise, which was seized last week by the Russian Coast Guard, after members tried to climb onto an Arctic offshore drilling platform, to draw attention to the environmental risks of Arctic oil-drilling.
Russia says it will question all the participants and detain "the most active" on piracy charges. Russia does not take prisoners when it comes to piracy - the charge carries a potential jail term of up to 15yrs and a fine of 500,000 rubles (about $15,500).
The oil platform, the first offshore rig in the Arctic, is owned by state-controlled gas company Gazprom. It was deployed in 2011, but its launch has been delayed by technological challenges. Gazprom had planned to start pumping oil this year, but no date's been set.
Greenpeace insists that, under international law, Russia has no right to board its ship and no grounds to charge its activists with piracy. It says that Coast Guard officers hit and kicked some activists when they stormed its vessel.
The activists hail from Argentina, Australia, Brazil, UK, Canada, Denmark, Finland, France, Italy, the Netherlands, NZ, Poland, Russia, Sweden, Switzerland, Turkey, Ukraine and the US.
They can count their lucky stars they're not being questioned by the KGB - they might never have been seen again!