Jeff was seven days into his journey in the Arctic. It was dark and terribly cold(-35oC). In face of this terribly low temperature. He had made good progress across the ice. Suddenly, the ice broke and one of his sledges fell into the sea. Jeff needed to get it back, so he had to put his hand into the ice-covered water.
请标准翻译
Jeff was seven days into his journey in the Arctic.
中的into怎么翻译?