As cultivators, as men, not to mention the plethora of things they had to go through since they've been in this prison dimension, the boys had more of a handle on fears than normal people or even most cultivators. So while there was a change in the behavioral patterns exhibited by the eyes in the river, it was still not enough to completely shake their confidence, as it stood they just decided to brace themselves and face whatever comes next with a calm and steady mind. So they just stood on the raft as it sailed towards the cave that the river flowed into and subsequently into the walls of the underground cavern they had found themselves.