I found this section the most suspenseful of any other section. I was on edge reading the whole thing waiting to see where the crew would end up. Being on those small boats for days just trying to get to any sort of land, even ice bergs, sounds horrendous. They traveled through the nights exhausted and soaking wet. I would think the most challenging thing would be to keep all of the boats from separating from one another. One big wave of open sea, you may never make it back. Shackleton handled it all pretty well though.
The worst thing that happened was in chapter 3 when the crew discovered that Worsley made a mistake in calculations and Shackleton changed their destination AGAIN. That killed a lot of the crews morale. That night was terrible as well with everyone thirsty and going to the bathroom all night while being docked in the middle of the sea. Shackleton constantly tried to keep everyone together and upbeat for their journey. He even told Blackboro he could go ashore Elephant island before anyone. Blackboro was too distraught to even move onto the island, Rickenson ended up having a heart attack, and Greenstreet's feet were frostbitten were hard to walk on. At least they were on land.