Venturing 600 miles north, the fleet encounters subzero temperatures and freezing spray. Sig sets into a tidal surge, but the extreme forces leave Clark injured. While Keith fishes through pain, Jake's risky pact unravels when a key man goes down.

Keith & Jake deploy guerrilla tactics when a factory trawler invades their grounds. At the Russian Line, Rick encounters temperatures so frigid that even snow crab can't survive on deck. Sig struggles against mounting breakdowns threatening his delivery.

When the Time Bandit loses power with a storm at its tail, Johnathan deploys a camera probe to find what's snarling his propeller. Keith sets a decoy string to lure Sig away from good fishing, but risks his own secret plan by trusting the wrong ally.

The crews and battered boats are feeling the brunt of one of the hardest Opilio seasons on record. While some crew members battle potentially catastrophic breakdowns to stay on the grounds and keep fishing, others throw in the towel and call it quits.

The Cornelia Marie uses US satellites to spy on the Russians, Scott pioneers a dormant fishery and Wild Bill faces off with a Russian greenhorn.

When Sig and Mandy disagree on a fishing strategy, Clark is caught in the middle. Wild Bill comes down hard on deckhands as Linda gets too close to danger. Keith pulls the Wizard alongside the Saga and unleashes unexpected bad blood.

As wintry weather pounds the fleet, a 30-foot wave crushes a Titan Explorer deckhand, threatening Jake's captaincy. On the Time Bandit, Johnathan loses a generator and goes dark. The Aleutian Lady drives into the weather to reach Dutch Harbor for repairs.

Captains scramble to meet an expanded quota in the path of a violent system dubbed "Squall-pocalypse". A breakdown on the Wizard puts Monte in debt to the Time Bandit and Josh and Casey exceed their own quota when it comes to injuries on deck.

Winter season erupts as the fleet battles the seas and each other; Sig and Rick's alliance shatters as Keith fights through an injury and a short-handed crew; the Titan Explorer loses steering in heavy seas, leaving Jake dead in the water.

Josh and Casey haul in their biggest pots ever, starting a gold rush to the Russian line. Captain Bill gets some inside intel, while Harvey confirms the numbers his own way. As Arctic Storm Elsa strengthens, the fleet realizes the ice queen casts a deadly spell.

When Sig's fishing information falls into the wrong hands, he deals his protégé a lesson he won't soon forget. After his crew gets slammed by back-to-back waves, Rick faces a gun-shy deckhand. Sophia contends with a crewman with a badly infected tooth.

A cracked tank on the Titan Explorer leaves Jake's engines vulnerable to seawater. Keith fires another deckhand but struggles to get rid of him for good. Johnathan prescribes alternative cures as the norovirus overtakes the Time Bandit crew at sea.

It's winter in Dutch Harbor and the fleet prepares to hunt Opilio crab. The season looks promising with the quota up and the price high, but tensions rise before the lines are thrown as one deckhand quits, two brothers fight and one goes overboard.

Saga loses a veteran deckhand, forcing Jake to steam a greenhorn army to the Russian line. Amid scuttlebutt that ports are closing due to a virus, Josh fights to get home for a reunion with his brother and Sig's daughter gets rushed to the hospital.

Sig gets tough news at sea forcing the Hansens to make a critical decision as John and Andy lend a hand. With wheelhouse ambitions, Jacob hits a wall with Keith on the Wizard. New captain Jack crosses a line when Harley makes a deal with Jake.

A new deckhand falls ill on the Time Bandit, raising questions for Andy and warning signs for John. A bait pallet breaks loose, forcing Captain Rick to deal with a severe crew injury. When Wild Bill's plan A fails on the Summer Bay, Maria tries plan P.

An early closure forces captains to work together to get their catch safely to port; Sig crosses a line when he repositions a rookie captain's pots; Jake and Sean race back from Adak while Linda bolsters her east coast reputation in the Bering Sea.

John risks capsizing after being forced to fish with a slack tank. Jake hauls in the largest seas of his career. Under pressure to get home for the arrival of Mandy's second child, Sig and Clark fish deeper than ever before as mechanical problems mount.

Sig strikes gold raiding Keith's hot spot, but when a line snarls his wheel, he must call his rival for help; a rogue wave knocks out Rick's electronics, forcing Bob to take the helm; Harley breaks in a new co-captain, only to break down at sea.

In the winter premiere, the snow crab fishery reopens unexpectedly after three years; Keith and Jake charge north, only to collide with an incoming Siberian storm; Sig and Rick form a wary alliance, but with big money on the line, trust fails fast.

Past the halfway point of the King Crab season, man and machine alike show signs of wear under the brutal hand of the Bering Sea. While repairs can be made to the equipment, the fishermen must dig deep to soldier on in a place where nature rules.

With unrelenting northerly winds bearing down on the fleet, every skipper steels himself for battle with the descending polar ice pack. And as temperatures drop on the grounds, tempers on deck flare up.

The polar ice pack invades the opilio crab grounds, forcing the captains to make a decision: grab their gear and run, or keep fishing and fight the floes. Two deckhands fall victim to an ice assault; a captain's troubles are compounded by a call home.

Two brothers find themselves in the same dire situation that sunk their father's boat. After a midseason hiatus, the fleet returns to the Bearing Sea, but the ice is back and worse than before. Now the skippers could get pushed past their breaking points.

Josh and Casey race to haul pots as engine failure threatens their delivery window. As seawater destroys his hydraulic motors, Junior attempts a risky high seas delivery of three new motors. Harley and his crew bang heads over his fishing strategy.