Captain Scott who had lead the Discovery Expedition would ask Crean to accompany him again in 1910 on the Terra Nova Expedition. He was part of the 3rd tier of the support party designed to help move the main exploration parties gear towards their destination so the main party could continue on well rested. On the return trip back to the main camp the 3 man group Crean was in became lost, food and supplies soon became short. The group made a decision to slide the sledges they had been dragging down a large icfeall they had been trying to hike around. Although almost impossible, they successfully slid down the 2000 foot slope all the while avoiding the large crevasses int he ice, some being upwards of 200ft wide. After two more days of hiking they reached the next camp site. This camp was only a teporary camp and the group still had to travel through two more temporary camps to reach the main base. On hike form the final temporary camp to the main base they realized their low food supplies were not going to last the 4-5 days it would take to drag the sleds the remaining 35 miles. Crean who was in the best condition of the group, was to walk the final leg and get rescue party. Equipped with nothing more than a few biscuits and some chocolate, he eventually reached the base camp at Hut Point after 18 hours of continuous walking through the arctic tundra. A rescue crew was soon sent out and successfully retrieved Creans two partners.
"In the winter it was once again Crean who was the mainstay for cheerfulness in the now depleted mess deck part of the hut."
The main expedition party Creans group had helped reach the final leg of the trip never returned to the camp at Hut Point. The remaining crew was forced to return to the more permanent arctic base at Cape Evans without the main team. During the trip across the solidified ice flow Crean, Apsley Garrard and Hanry Bowers set camp on a unstable section. The section of ice let go during the night leaving the men suck out on a moving ice flow. Crean jumped from floating chunk to floating chunk eventually reaching solid ground. He then gathered a party together to retrieve the two men still stuck out in the flow. Both men were successfully rescued.
Crean is most well known for his heroics during Shackleton's Endurance Expedition. After having their ship, the Endurance, destroyed after it had become stuck in an ice flow, the crew was forced to march across the ice dragging their supplies in the ships 3 life boats. They eventually reached Elephant Island were a temporary camp was set up. They were still trapped in the arctic with no way of sailing home, the only chance the party had of rescue was to sail one of the small lifeboats to a whaling station on South Georgia for help.
The sturdiest of the boats, the James Caird, was chosen for the trip. The crews carpenter worked with what little was available to make the vessel more seaworthy. Shackleton originally selected Crean to stay behind to help keep the rest of the party alive, but Crean begged to be allowed to help on the sail to South Georgia. The crew of 6 set off, and battled 30 foot swells and force 9 winds for 17 days before making landfall on the far side of South Georgia. Shakleton then selected Crean and another man, Worsley, to go with him on the 36 hour trek to get across the island to the whaling station. Eventually, after successfully reaching the station, a rescue team was sent out to retrieve the crew that was still trapped on Elephant Island. All members of the Endurance Expedition would survive.
"He always sang when he was steering, and nobody ever discovered what the song was, but somehow it was cheerful".Shackleton