Zhang Tie could reach his fastest speed by sea. The ocean was his highway. Additionally, he would not be discovered by people in the ocean.
Zhang Tie could move about 670 m per second in the ocean. Although this speed was less than half of the transmission speed of sound in water, it was already super fast for any other living beings in the ocean.
The distance between Yingzhou Province and Youzhou Province by sea was about 8,000 miles, which was similar to the aerial distance.
It would take Zhang Tie 2 months to finish this distance by airship; however, it only took him less than 3 days by sea.
Zhang Tie had arrived at Youzhou Province on the evening of May 18.
