Greenpeace activists chained themselves to the anchor chain of the arctic rig support vessel Anna Akhmatova on Monday.
The group is the same one that stormed Gazprom's Prirazlomnaya oil rig Friday to protest the state-owned energy company's plans to drill in Arctic waters.
Early Monday morning, inflatables launched from the Greenpeace vessel Arctic Sunrise approached the Anna Akhmatova, which carries workers to and from the rig, and attached themselves to the vessel's anchor chain.
Greenpeace said in a statement that by 9 a.m. Monday morning 14 activists from 10 different countries were in boats attached to the Anna Akhmatova, preventing it from raising anchor and moving to the rig to complete work necessary for it to start drilling work.
The group said a "tense standoff" was under way mid-morning, adding that the Russian coast guard arrived on the scene but took no action.
By late afternoon, the activists were still chained to the supply vessel, despite Gazprom workers firing cold water at them from the Anna Akhmatova's onboard water cannons.
"So much water, sometimes all you saw was white. Felt like we were in a hurricane," Greenpeace cited one of its activists as saying on its official Twitter account.
The environmental organization later tweeted that one of its inflatables had been flipped over by a powerful jet of water but that another team of activists moved into position shortly afterward.
When reached by phone, Gazprom referred inquiries to Sevmash, the Severodvinsk-based shipbuilder that operates the Anna Akhmatova, but a Sevmash spokesperson declined to comment.
Monday's protest is the latest episode in the Greenpeace campaign to draw attention to the ecological consequences of Arctic drilling.
Environmentalists have warned that no technology yet exists to clean up oil spills in icy conditions, and they say even a small accident could be catastrophic for the Arctic ecosystem.
On Friday, six Greenpeace activists scaled the side of the Prirazlomnaya rig and displayed banners that said "Save the Arctic" and "Don't kill the Arctic." The activists left after 15 hours, accusing Gazprom workers of hurling cold water and metal fragments at them in similar efforts to dislodge them.
Gazprom Neft Shelf's Prirazlomnaya oil platform is the world's first ice-resistant oil rig and is expected to produce more than 6 million tons of oil a year when fully operational.
The Prirazlomnoye oil field, beneath shallow waters in the Pechora Sea, is thought to hold about 70 million tons of oil.