Activists have reported being confined for 23 hours a day in bleak, sometimes ice-cold cells in Murmansk, a port city above the Arctic Circle whose remote location complicates access for lawyers and consular officials.The Kremlin has essentially rejected Greenpeace head Kumi Naidoo's offer to travel to Russia and stand as security for the release of the detainees, who come from 18 nations on five continents.