'No Amnesty for the Arctic'
Greenpeace argues that the Gazprom rig is an environmental catastrophe waiting to happen that risks ruining the pristine Arctic ecology of the southern Barents Sea where the deposit is located.
Ben Ayliffe, Arctic campaigner at Greenpeace International, vowed that the group would not let up in its campaign to save the Arctic environment.
"We're relieved the Arctic 30 are going home, but they should never have been charged in the first place.
"We will not stay silent while companies like Gazprom and Shell line up to profit from the Arctic's destruction. Today is only the end of one chapter and we start another.
"There has been no amnesty for the Arctic and this is far from over," he said in a Greenpeace statement.
The Kremlin amnesty came less than two months before the start of the Winter Olympic Games in Sochi, and critics have described it as an attempt to shore up Russia's human rights image ahead of the Games.
The two jailed members of Pussy Riot punk band, Nadezhda Tolokonnikova and Maria Alyokhina, were freed on Monday after benefiting from the same amnesty.
In apparent defiance of Greenpeace, Gazprom earlier this month announced launching oil production at the Prirazlomnaya oil rig that had been the target of the activists' actions.