Joel builds a watercraft capable of carrying his team and supplies across the Alpine Lake.

Tamra builds a shelter capable of keeping her team safe during the heavy rainfalls present in the Spruce Forest, as well as a bridge to grant access across a crucial stream running through the forest.

Matt builds a seasonal hunting camp in the Chalk Creek hunting grounds.

The 2008 Iditarod race begins. Returning champion Lance Mackey already has a hitch in his plan. Iditarod icon DeeDee Jonrowe loses her dog team outside a checkpoint. The mushers prepare to face the dreaded Alaska Range.

The mushers cross the treacherous Alaska Range. Jonrowe faces "the Step," where she was injured last year. Injury also causes Mackey's lead dog to be dropped. Martin Buser takes a strategic rest at Salmon River before beginning the trek again.

With the Alaska Range behind them, mushers now must rest -- a strategy all its own. Mackey, already down a lead dog, cares for his exhausted team. Jonrowe, nursing a virus, is first to the half-way mark, winning Yukon Gold, but at what price?

Mackey makes up for lost time while King devises a new plan. Eskimo Nelson debates whether to withdraw from the race. The Busers separate to allow former champion Martin a chance to go for the gold.

Mackey continues to break trail for rival King but is catching on to King's game. Rookie musher Holt, making a slew of beginner's mistakes, has to decide whether he can carry on or if he will succumb to the treacherous nature of the Iditarod Trail.

With Nome less than 100 miles away, Mackey, King, and Martin Buser battle for the finish line. Icon Jonrowe battles to stay in the top 10, and for rookie Holt, just finishing Alaska's toughest race means winning.

Meet Ben Lecomte, the long-distance swimmer making the historic swim across the Pacific Ocean. Find out how the Seeker crew and research teams are collecting data to raise awareness of the state of our ocean's health.

Preparing for Ben Lecomte's swim took many years and was complex. Plus the Seeker crew has had to adapt to months on a boat, including creating their own water, preparing meals, and changes in their hygiene and sleeping.

When planning a journey as long as Ben Lecomte's swim across the Pacific, how does the Seeker crew plan the ideal route and what science is used to create the best path? We look at the role of ocean currents and how research supports Ben's swim.

As three typhoons converge upon them in the middle of the Pacific, the Seeker crew must make their most deadly decision yet: face the massive storms head on, or turn around and retreat to the safety of land.

As Ben Lecomte slowly swims across the Pacific Ocean, the Seeker crew records audio of surrounding marine life. These hydrophone recordings provide a rich view into marine life that's never been done before for this length of time.

Swimming for 8 hours a day for months has a profound impact on Ben Lecomte's center of gravity, muscles, and bone density. How does this compare to an astronaut in space? We look at what changes in Ben's body he might expect by the end of his swim.

Learn about the ambitious nutrition plan Ben Lecomte must plan for to power eight hours of swimming per day across the Pacific Ocean. What effect will months at sea have on Ben's microbiome––and can we harness that knowledge for our own health?