Greenpeace says six activists opposed to offshore drilling in the Arctic have abandoned a Seattle-bound drill rig they boarded in the Pacific Ocean six days ago.

The organization said in an email Saturday that rough seas prompted the decision. The protesters rappelled off the rig and got into inflatable boats before returning to a Greenpeace ship stationed nearby.

The six climbed the Polar Pioneer about 750 miles northwest of Hawaii on Monday. A heavy-lift vessel called the Blue Marlin is transporting the rig to Seattle for staging before possibly heading to the Arctic.

Royal Dutch Shell, which leased the rig, sued in U.S. District Court in Anchorage, Alaska, last week seeking a court order to remove the protesters. A judge heard arguments on Friday but declined to rule immediately.