The Fennica leaves Portland. OPB/John Rosman photo.

Arctic drilling is under way.

Shell Oil confirmed Thursday night that its Polar Pioneer rig sent a 20-foot-wide drill bit spinning into the floor of the Chukchi Sea about 5 p.m. Alaska time.

It came at the end of one of the most eventful days in the company’s eight-year effort to find oil in the Arctic Ocean.

“This is a significant milestone. A lot of people have worked very hard to get us here,” Shell spokeswoman Megan Baldino said.

More than 2,000 miles away from the Chukchi Sea, just a few minutes before the giant drill bit hit the sea floor, the company’s icebreaker Fennica managed to free itself from a blockade of protesters in Portland, Oregon.

Protesters had suspended themselves from a bridge across the Willamette River.

Others had taken to kayaks to block the exit of the Fennica.

Thursday morning, the Fennica approached the bridge, then turned around after a 15-minute standoff.

Shell’s Fennica vessel in Unalaska shortly before heading to Portland for repairs. Photo: John Ryan/KUCB.

A federal judge in Anchorage slapped Greenpeace with a $2,500 fine for every hour its activists blocked the Fennica.

By late afternoon, local police and the U.S. Coast Guard had disbanded the protesters. The Fennica set sail past the bridge and headed for Alaska.

Greenpeace called delaying the icebreaker for 36 hours a victory.

Activists say climate change and the risk of an oil spill make drilling in the Arctic Ocean a dangerous mistake.

Shell has begun drilling a 35-foot-deep pit into the sea floor for housing a well-blowout preventer.

"It’s drilled to allow what’s called a blowout preventer to sit beneath the sea floor," Shell's Megan Baldino said of the pit known as a mud-line cellar. "In the event there’s any sort of ice scour or underwater ice movement, it protects it because it’s sitting in this 20 by 35 foot excavation.”

Shell can only begin drilling into oil-bearing layers, much deepter beneath the sea floor, after the Fennica arrives at the drill site in the Chukchi Sea.

Interior Department officials said last week they expect to approve the deeper drilling quickly once the Fennica has returned to the Arctic.