Sobek's journey was rather slow. Certainly not for the long road: since he could now reach 170 km/h, if he wanted to he could cover the distance that separated him from humans in less than five hours.
The fact was that he wanted to thoroughly clean up every stretch of the river he passed through of all available fishes. That way he could level up and keep growing as he traveled. The preys in the river wasn't as abundant as in the swamp, but still they provided him a good amount.
On the first day, he had covered 100 kilometers and gained 53,000 experience points. The second day he had covered another 130 kilometers and gained 66,000 experience points. He had therefore managed to cover abundantly the 100,000 experience points required to level up, reaching level 17.